Erik Hansson

Uppsats för avläggande av naturvetenskaplig magisterexamen i Miljövetenskap 30 hp Institutionen för växt- och miljövetenskaper, Göteborgs universitet November 2010

Groundwater on Zanzibar - use and pollutants

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SUMMARYSUMMARYSUMMARYSUMMARY

Groundwater is the major source of drinking water on Zanzibar. The aim was to

identify how the groundwater is used in some selected areas on Zanzibar. Interviews

were conducted with people in 6 villages (Jambani-Kikadir, Jambiani-Kibigija, Paje,

Bwejuu, Chwaka and Uroua). Each village was visited 3-4 days, and on average 30

persons, mainly women, were intervieved in each village. In addition the manager or

person in charge at all hotels and guethouses in these villages were interviewed. All

interviews were made in Kiswahili by the assistance of an interpreter. Water samples

from each village were taken analysed for nutrients (ammonia, nitrate and phosphate).

Determinations of salinity, conductivity, TDS (Total Dissolved Solids) and water

temperature were made in the field.

The measured levels of nutrients indicated that the groundwater was often affected by

sewage. The levels were in many cases well above the guidelines suggested by WHO

and the Swedish National Food Administration. The source of contamination is

probably the sewage-pits used in all villages.

All villages except Paje has problems with salinity in the wells. In Bwejuu the

problem was not so bad, but in the other villages everyone considered salinity to be a

major problem. Measurements of salinity confirmed this picture, even if Paje and

Bwejuu had lower salinity in their wells. The reason for the high salinity levels in the

wells is saltwater-intrusion from the ocean.

Chwaka had an organized system for collection of drinking water. This was taken

from the village of Gendele, approx 5 km west of Chwaka. The cost for this water was

200 Tsh for the transport (per person) and an additional 50 Tsh for every (20 litre)

bucket that was brought back. Many of the villagers could not afford this, so they had

to drink the saline water from their village instead.

During the rainy season it is common practice to collect rainwater in all villages. The

rainwater is mainly used for dishes and laundry because it is very soft compared to the

well water. This reduces the amount of soap to be used, and it also preserve the

colours to the clothing. The use of household water was as follows: Laundry (29%),

Shower (29 %), Cooking (13 %), Dishes (13 %), Other (8 %), Drinking (5.5%).

Average water use per person per day throughout the area was 32.5 litres.

During the interviews a total of 372 complaints on water quality were registered. They

were as follows: Salinity (66 %), Bad smell (17 %), Causing illness (8 %), Insufficient

quantity (4 % in wells), Insufficient supply (3 % in pipes), Dirt (1 %). The problem

with illness connected to drinking water could be bigger than indicated above. Some

people could not see any connection between drinking (bad) water and getting sick,

they thought that illness was caused by the Gods or just occurring without any

specific reason. Most people consider illness caused by water to be a problem

mainly/only during the rainy season.

The majority (76 %) of the interviewed regularly used more than one well for their

household water, mainly for reasons of salinity, quantity and access. When using

more than one well for salinity reasons, the closest one was often used for dishes and

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laundry and the more remote one for cooking and drinking. Average family size

throughout the villages was 5.3 pers.

The sewage was either disposed in a latrine pit at home or the beach/forrest. In Paje

almost everyone has a latrine pit in their home, while in Uroa almost everyone uses

the beach/forest. The other villages were somewhere in between. The solid waste was

either put in a pit burned regularly, or disposed on the beach to be removed by the

tide.

Most people considered pipewater to be better than well water. They believed that

pipewater was treated in some way and therefore much cleaner and safer. The

pipewater is, however, not treated in any way in the villages. People in villages

without pipewater have a strong desire to be connected to a pipe. But most of them are

not prepared to pay anything for it. Presently, the villagers have free access to their

water. But the hotels/guesthouses have to pay a fee to the water department. The size

of the fee is based on an estimation of how much water the hotel uses. For a 40 bed

guesthouse is was 6000 Tsh per month. No conflicts between villagers and

hotels/guesthouses about water use were noticed.

In villages with pipewater, the wells were hardly used at all as long as there is water

in the pipe. When the pipewater fails, however, people starts using the wells again.

Since the water haas been standing still for a long time, this may cause problems with

diarrhea among the villagers.

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FOREWORDFOREWORDFOREWORDFOREWORD

This study focus on the use of groundwater quantity and quality on Zanzibar. Effects

of the rapidly increasing tourism were studied, to determine how much they affect the

water resources for the local inhabitants. The reason for these studies was to get a

better picture of how people living in coastal communities use their water and what

problems they experience. Since many people are living in coastal areas or on islands

around the world, where the only available water is either groundwater or saltwater,

the results from this study could also be used to understand fresh water problems on

other, similar places.

The study was funded by EU with my supervisors being Ron Johnston at University

of Stockholm and Dan Strömberg at University of Gothenburg. The field work was

conducted on the island of Unguja, the main island on Zanzibar. I had my office in

Zanzibar town, at the facilities of Institute of Marine Sciences, University of Daar Es

Salaam, where I also did my laboratory work. The study was carried out between

November 1995 and March 1996.

Erik Hansson

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CONTENTSCONTENTSCONTENTSCONTENTS

SUMMARY............................................................................................................................................. 1

FOREWORD .......................................................................................................................................... 3

CONTENTS ............................................................................................................................................ 4

INTRODUCTION ................................................................................................................................. 5

THE AFRICAN SITUATION ..................................................................................................................... 5

ISLANDS: A PARTICULAR SITUATION ..................................................................................................... 6

ABOUT ZANZIBAR ................................................................................................................................ 7

THE AIM OF THIS STUDY ....................................................................................................................... 9

MATERIALS & METHODS ................................................................................................................ 9

SELECTION OF VILLAGES ...................................................................................................................... 9

INTERVIEWS ....................................................................................................................................... 11

ASSESSMENT OF INTERVIEW RESULTS................................................................................................ 11

SAMPLING .......................................................................................................................................... 11

CHEMICAL ANALYSES ........................................................................................................................ 12

RESULTS.............................................................................................................................................. 12

INTERVIEWS ....................................................................................................................................... 12

WATER SOURCES ................................................................................................................................ 16

VILLAGE SEWAGE SYSTEM................................................................................................................. 18

SOLID WASTE TREATMENT ................................................................................................................ 19

GROUND-WATER CHEMISTRY............................................................................................................. 19

DISCUSSION........................................................................................................................................ 22

WATER SOURCES................................................................................................................................ 22

WATER QUALITY................................................................................................................................ 25

USED AMOUNTS OF WATER ............................................................................................................... 28

SEWAGE TREATMENT ......................................................................................................................... 29

SOLID WASTE TREATMENT................................................................................................................. 29

THE FUTURE ....................................................................................................................................... 30

CONCLUSIONS................................................................................................................................... 32

REFERENCES ..................................................................................................................................... 32

ANNEX A QUESTIONAIRES........................................................................................................... 34

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INTRODUCTION

The access to clean freshwater has decreased in many regions in the last decades. This

problem will not decrease in the future, instead it will probably increase. There are

several reasons for this, but most of them are related to misuse of water-resources,

pollution or simply the pressures related to increased population density. It has been

estimated that today more than one third of the worlds population lack safe drinking

water or adequate sanitation. The population is steadily growing in most developing

countries, increasing the pressure on available water resources. Not only is the

population increasing, it is also moving towards coastal areas, putting even larger

pressure on these areas.

The consumption of fresh water has a tendency to increase faster than population

growth. This is because of increased standard of living in many areas, can

concurrently lead to increased water use by new industries, increased irrigation and

the adoption of water use methods which are more “luxurious”, and less in line with

environmental limitations; for example the increased frequency of bathing, automated

washing-machines and similar activities. In most third world countries irrigation is by

far the major use of freshwater.

With increasing population, the pollution of water also increases. The sources for

pollution are many. In most developing countries there are no sewage treatment

facilities at all. This causes large contamination with pathogens of groundwater, as

well as of nearby rivers and lakes, the very same places that is often used for washing,

bathing and even drinking. It has been estimated that as much as 80% of all diseases

that are spread in developing countries are carried by infected fresh water, and that

25.000 people dies every day because of polluted or infected freshwater (Cunningham

and Saigo, 1995). The increased use of fertilisers and pesticides in agriculture

increases pollution of both surface waters and groundwater. These substances are

often used in excess and eventually reach freshwater resources, making them useless

for household purposes. A further problem related to population growth is that more

land surface area is covered by roads and buildings etceteras. This kind of

constructions can prevent the precipitation reaching the aquifers since residence time

of the water on the surface will increase, evaporation will therefore increase, and rain

is also diverted from the recharge zone of the aquifer. This means that the aquifer will

not be replenished, and thereby being emptied faster.

Furthermore, in coastal areas, extensive pumping of groundwater can result in

saltwater intrusions from the ocean, rendering the groundwater unfit for drinking and

irrigation. Once groundwater is polluted, it can remain polluted for a very long time.

This time depends on the type of soil, the rate of groundwater recharge and the

amount of pollutants being added. Similarly if too much groundwater is withdrawn

from the aquifer, this can cause the water-containing pores to collapse, which means

that the water carrying capacity of a bedrock regime is lost for ever.

The African SituationThe African SituationThe African SituationThe African Situation Africa is suffering from many of the problems that are connected to lack of fresh

water. Many areas receive little precipitation, and suffers from overgrazing and

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overpopulation. The most well known problem in Africa is probably the droughts

which occurs in many areas, causing the harvest and cattle to die, leading to starvation

and death among local people. This problem is mainly found is the Sahel-zone and in

southern Africa. It has been estimated that in Ethiopia 94 % of the population lacks

access to clean water, and in Mali 88 % (Cunningham and Saigo, 1995). These cyclic

droughts have probably always occurred, but their effects has become more

devastating because of the increased population and more intense use of soils. In areas

in Africa where rainfall is low, groundwater is a very important resource. It is the

main source of water for many rural people throughout the region. Groundwater in

arid regions can be salty, especially old groundwater which has slowly dissolved salts

from the surrounding rocks or soil over thousands of years.

In most parts of central Africa there is no actual lack of fresh water. They regularly

receive a fair amount of rain, recharging the freshwater reservoirs. Areas like

Tanzania is not experiencing any major lack of water during most parts of the year,

but with increasing population matters will become worse in the near future. The

growing population means that agriculture must be producing more food to be able to

feed the people. Since the area of potentially arable land is limited, this means that the

use of irrigation and fertilisers must increase. Both these factors pose a threat to the

groundwater since over-use and pollution can be the result. In southern Africa

irrigation accounts for between 60 and 75 % of all water use. 60% of this water is

wasted, not reaching the plants, but instead evaporating or being lost as runoff. Areas

receiving less than 600 mm of rain annually can not produce crops unless there is

some supplementary water. The heat from the sun or hot winds makes as much as

85% of the rain to evaporate before it can be accessed by the plants.

Islands: a particular situationIslands: a particular situationIslands: a particular situationIslands: a particular situation Islands like Zanzibar are often completely dependant upon groundwater for their

freshwater needs. On islands of this size, there are rarely any rivers or lakes big

enough to meet the needs for fresh water from the local communities. This makes

them even more vulnerable to misuse of the limited resource that groundwater in fact

represents.

The coastal populations are steadily growing. This combined with a growing tourist

industry on many tropical islands, bringing new large hotels, is steadily increasing the

demands of fresh water. The hotels catering for tourists use large amounts of fresh

water, for i.e. showers, sanitation and pools.

One of the major problems experienced on islands and coastal areas when large

amounts of groundwater is withdrawn, is saltwater intruding into the aquifers. Once

saltwater has entered the aquifer, the aquifer can be considered permanently destroyed

since the turnover time for groundwater renewal is usually very long (100’s of years).

There has been warnings that even moderate pumping of groundwater from coastal

aquifers in Tanzania could result in saltwater intrusions. When the groundwater-table

is lowered one meter, the saltwater-table rises 40 meters. This phenomena occurs

because of the differences in physical properties between fresh and salt water.

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A threat that might affect low-lying coastal areas in the future is global warming. If

the average temperature on earth rises this will cause the sea-level to rise, and thereby

threatening aquifers near the coast, since saltwater intrusion will occur more easily.

About Zanzibar

General facts

Zanzibar is an island state belonging to Tanzania, and is located in the Indian Ocean

approximately 30 km east of the Tanzania mainland. The state of Zanzibar consists of

three islands; Pemba Island, Unguja Island, and Latham Island. Unguja is the main

island, and is usually referred to simply as Zanzibar. Zanzibar town, the capital of the

islands, is located on south-western Unguja The population on Pemba is 340,000

people, and approximately 365,000 on Unguja whilst Latham island is uninhabited.

Approximately 110,000 people live in Zanzibar town and the current rate of

population growth on Zanzibar is approximately 3% annually. The rural population

lives in small settlements or villages with up to 3000 inhabitants, scattered around the

islands. The main sources of income is agriculture, fishing and, on the east coast of

Unguja, seaweed farming. Average income per pers is q TSh. In the following parts of

this report the name Zanzibar will refer to only the island of Unguja unless otherwise

stated.

Geology

Zanzibar and Pemba are parts of the ancient Miocene Rufiji/Ruvu delta, and remain

above sealevel as land-blocks of the original delta. Most parts of Unguja consists of

rugged limestone which is frequently cavernous and with many solution channels. On

central Zanzibar is corridors with good aquifers found. These are partly recharged by

a deep aquifer reaching Zanzibar from the Tanzanian mainland. The south-eastern

part consists of a porous limestone, with a fresh-water lens covering deep-lying

seawater. The recharge of the freshwater is mainly by rainfall.

Vegetation

The island used to be covered by rainforest, but today is only a small part left. The

rainforest has been replaced by extensive plantations of mainly rice, cloves and

coconuts. The eastern parts of Zanzibar are largely covered by impenetrable bushes.

Tourism

Prior to the second half of the 1980’s tourism was almost non-existing on Zanzibar,

due to restrictions on foreigners’ freedom of movement. Since then, the situation has

changed dramatically and the island is experiencing a real tourist-boom today. The

area that was initially developed for tourism was, except from the town itself, the

village of Jambiani, together with some smaller developments in Bwejuu and Paje.

Since these areas lacked electricity at that time, the guests were mostly backpackers

and other low-budget travellers. These areas are still very popular with travellers, but

Nungwi, on the northern point of the island is becoming increasingly popular. A new

feature is big luxury resorts, mainly for charter tourists from Europe. The first luxury

resorts were constructed in the early nineties, and at the end of 1996, 7 could be found

with 2 more under construction. These hotels offer the highest standards possible, and

their guests rarely visit any part of the island outside the hotel area, except excursions

to Zanzibar town. Several middle-class hotels are found on the island as well. These

are mainly found along the east coast from Chwaka northwards. These hotels receive

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both charter-guests, booking their vacation at home, and guests booking the stay once

they have reached Zanzibar. The standard is intermediate the back-packer guesthouses

and the high-class hotels.

The Integrated Planning Unit (1993) has described plans for future tourism

development in the Paje-Uroa area, which includes construction of new hotels with

room for almost 2000 tourists. This can be compared with the 750 beds available in

the area today.

Climate

The climate of Zanzibar is dominated by two rainy seasons with drier periods in-

between. At the end of March the Masika rains, or long rains, from the south starts.

This is the main rainy season when most of the precipitation falls. From end of May

until early November is the cool season. This means day temperatures around 28oC

and night temperatures around 19oC. This is followed by the Vuli rains, or short rains,

from north-east which lasts until end of December. These rains are not as intense as

the Masika rains. January to end of March is the hot season with temperatures

between 32oC (day) and 23

oC (night).

The Masika rains are the most important for groundwater recharge with the water

table recovery being almost double that during the Vuli rains. During the heavy rains

the infiltration is rapid and elevated water tables are registered almost immediately. It

is unusual that streams flow into the sea though, except for two well-defined

catchments in the mid-north Western region discharging into Makubwa Bay. The bulk

of precipitation percolates directly through the coral rag before reaching the coast.

General Water Use

The most common water-source in rural areas are wells. They are usually located

within the villages, but in some cases wells way out of the village are used due to

problems with the water quality in the village wells.

Some villages use water from more distant sources, which is pumped to the village

through a pipe system. The pipe ends in a number of taps within the village. Most of

these taps are public ones used by several households, but a few households has a tap

inside the house. These pipe systems experience frequent failures, so therefore wells

are important water-sources in these villages as well.

The main use of the ground-water is for household purposes, i.e. for cooking and

washing. The amounts used for agriculture are comparatively small, except for some

parts of the central island.

According to Drangert (1993), the minimum use per capita per day of water should

be: 2-4 l for drinking, 1-2 l for cooking, >1 l for dishing, >1 l for laundry, >5 l for

washing. For good health at least 20-25 litres should be used. In villages in inland

Tanzania with limited access to freshwater during dry season, people survive on as

little as 5.1 litres per person per day (Drangert, 1993).

General Sewage and Garbage Handling

In the villages the two ways to handle sewage is either to dig a latrine pit in the house

or to utilise the beach or the forest. The latrine pits are simply a hole in the ground

9

where the effluents slowly leaks out into the surroundings. The beach is only used

when it is dark, and the leftovers are removed by the tide. The beach variant is the

traditional way to solve the problem, latrine pits has been introduced in recent years

by the municipal authorities (Per P-L).

The traditional composition of the solid waste from the households has been organic

leftovers, mainly from the food. In the past few years plastic has become more widely

used, as plastic bags and wrappings, changing the composition of what is thrown

away. The disposal of metallic is not very big, consisting mostly of tin cans.

The solid waste is most commonly put in a pit in or near the village. When the pit is

full it is burned and filled up again. When the pit eventually gets full, it is covered

with dust and a new one is made. The other way to get rid of the solid waste is to put

it on the beach, where the tide removes it.

The aim of this studyThe aim of this studyThe aim of this studyThe aim of this study

The aim of this study was to identify how the groundwater is used in some selected

areas on Zanzibar. The use was related to quality and availability of groundwater, as

well as population density and tourism.

MATERIALS & METHODS

Effects of the rapidly increasing tourism was studied, to determine how much it

affects the water resources for the local inhabitants. The reason for this study was is to

get a better picture of how people living in coastal communities use their water and

which problems they might experience.

Selection of villages

The investigated area was the coastal strip between the two villages of Jambiani-

Kikadir and Uroa. These are located almost 30 km apart in a north-south direction, on

the south-east coast of Zanzibar. These villages, with seemingly similar ambient

conditions, differ however in some aspects. They represent villages with good or bad

well-water, good or bad pipe-water, well-developed tourism within the village or no

tourist facilities in the village. This study will try to find out if there are any

differences in water use due to water quality, or if the quality might be affected by

heavy water-use from the tourists.

Based on a preliminary survey of the East coast of Unguja, the following villages

were chosen as the basis of the overall study:

Jambiani-Kikadir

Population: 2795

Income generated from: Seaweed farming, fishing, agriculture

Water supply systems: pipe, water coming from a cave 3 km NW of village.

Same cave as Jambiani-Kibigija; Wells, approximately 14.

Number of guesthouses in village: 6

10

Jambiani-Kibigija

Population: 3442

Income generated from: Fishing, Seaweed farming

Water supply systems: Pipe, water coming from a cave 2 km W of village.

Same cave as Jambiani-Kikadir; Wells, approximately 30.

Number of guesthouses in village: 6 (+3 under construction)

Paje

Population: 1750

Income generated from: Seaweed farming, agriculture, fishing

Water supply systems: Wells, approximately 20.

Number of guesthouses in village: 4

Bwejuu

Population: 2620

Income generated from: Seaweed farming, fishing

Water supply systems: Wells, approximately 16.

Number of guesthouses in village: 8

Chwaka

Population: 1820

Income generated from: Fishing, Seaweed farming

Water supply systems: Pipe, water from Ufufuma, ca 3 km W of village; Wells,

approximately 10.

Number of guesthouses/hotels in village: 1 hotel, 1 guesthouse

Uroa

Population: approximately 3000

Income generated from: Fishing, Seaweed farming

Water supply systems: Pipe, water from a well 500 m W of village; Wells,

approximately 8.

Number of guesthouses/hotels in village: 5

In the following parts of this report Jambiani S refers to Jambiani-Kikadir and

Jambiani N to Jambiani-Kibigija. If only Jambiani is used, it refers to both villages at

the same time. The population numbers refers to 1995 in most cases.

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Interviews

In order to establish the current water usage patterns, problems with water, and other

water related issues, a questionnaire was designed. The questionnaire posed questions

on the amounts of used water, what the water was used for, problems with the water,

as well as solid waste and sewage treatment. It was used both for villagers and

hotels/guesthouses, with some modifications to allow for the differences in end-point

goal of the water use between private dwellings and businesses. An entirely different

questionnaire was given to the Sheha (village chief) in each village to get general

information on the economic and cultural status of the village. The questionnaires can

be found in Annex A.

Each village was visited during 3-4 days in order to conduct the interviews. The way

the villagers were picked was simply by walking through the village and interviewing

the people encountered. It was ensured though that people from all parts of the village

was interviewed so that problems connected to any specific well were detected. An

average of 30 persons was questioned in each village, with a total of 193 persons,

most of them women. The reason for mainly talking to women is that since they are

the ones collecting water they are most aware of how much water they use and any

problems related to the wells. To estimate the amount of water people used, they were

asked how many buckets of water they use for each task. Since the buckets generally

used are 20 litre buckets, it was easy to convert number of buckets to litre. It was

ensured for each person that she/he referred to 20 litre buckets. All of the guesthouses

and hotels in the area were also visited. The manager or, if he was not present, the

person in charge was asked the questions. All interviews were conducted in Kiswahili,

using an interpreter from the Institute of Marine Science. Khayrat assisted in Paje and

half of Bwejuu, and Mwadini assisted for the rest of the time. The Sheha accompanied

during many of the interviews.

Assessment of Interview Results

During the interviews the answers to some key questions was compiled to find out

which problems were experienced with water in the villages; were they were found

and how big they were. Based on these answers, four wells in each village were

sampled for analysis of nutrients. Water from these wells, together with several other

wells, were also analysed for salinity, conductivity, TDS and temperature.

Three of the wells picked for nutrient analysis were wells that the villagers reported

had some kind of problem (i.e. smelly, causing illness). The fourth well was one with

no or only minor problems, used as a reference-well.

Sampling

The villages were revisited to locate the wells and to collect some general information

on the wells (i.e. when they were constructed and to store their co-ordinates by using

GPS). The wells were located by asking the people who had complaints on water

quality to show which well they were referring to. All the wells were given an ID

consisting of three letters and a number. This ID, together with a description of the

well-location and its position is found in appendix A.

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The village was then visited one day each for sampling. The sampling period was

chosen to correspond with maximum tide level difference (spring/neap-tide). Samples

was taken at both maximum high tide and at minimum low tide. A clean bucket was

used to take water from the wells in order to avoid contamination related to public

buckets. The samples was filtered, using a syringe and glass filters, and stored in 20

ml plastic containers (one for each sample). They were stored on ice until reaching the

laboratory. For time of sampling and tide timetable, see appendix A.

The ammonium analysis was conducted at the Institute of Marine Science (IMS) in

Zanzibar town the same day as the samples were taken, while the rest of the samples

was frozen for later analysis. Phosphate analysis was conducted at IMS during two

days shortly after the sampling period, and the nitrate analysis was done in Sweden.

The reason for measuring these parameters is that the nutrients indicates antropogenic

influence from e.g. sewage. High salinity-level is a good indication on saltwater-

intrusion resulting from excessive water-use.

Chemical Analyses

Ammonia and phosphate analyses were conducted using the spectrophotometric

methods of Parsons et al., (1984) on site in Zanzibar The nitrate analyses were done

in Stockholm. The measurement of salinity, conductivity, TDS and water temperature

was done in the field, using an WTW TDS/conductivity meter, calibrated against

standards.

RESULTS

Interviews

The aim with the interviews was to examine water usage patterns and to identify

problems connected to the use and quality of groundwater. Clearly there were a

number of items that were considered to be significant problems by the locals as well

as the hotel managers. The interviews showed that salinity was the single factor that

affected the usage pattern most. It is also clear that the quality of water is a much

bigger problem than low quantities. In the following chapters will the results from the

interviews be presented, both for the villages and the hotels.

Interviews with Villagers

A total of 193 people, most of of them women, were inteviewed. The numbers for

Uroa also includes the small village of Dikoni, which is located just outside Uroa.

Interviews with Hotel Managers

A total of 27 hotels and guesthouses were visited. Most of them have guesthouse

standard (i.e. low standard). One guesthouse in Paje was not visited since it was

closed, and a couple of small guesthouses north of Bwejuu were not visited either.

Village Number of hotels/guesthouses Number of beds

Jambiani S 6 255

Jambiani N 5 64

13

Paje 6 90-100

Bwejuu 4 123

North of Bwejuu 2 450

Chwaka 2 52

Uroa 3 32

Table 1: Distribution of hotels and guesthouses in the area

The occupancy rate differed a lot between the hotels. In general, the reported

occupancy rate ranged between 50 - 70 % during high season (late June until early

September, and mid December until end of January), with some of the smaller

guesthouses only reporting between 10- 20%. During low season (rest of the year

except the rainy season), most places said that between 5-10% of the beds was used

by guests and many of the smaller ones reported 0%. During the rainy period from

mid March until early June everyone said that the occupancy rate was 0%. In the four

southernmost villages, most of the hotels and guesthouses are located within the

village itself. In Chwaka and Uroa, they are located outside the villages though.

Quantities of used water

The interviews with the villagers showed the average water use per person per day

throughout the area to be 32.5 litres for domestic use. There were no significant

differences between the villages. If family-size and water-consumption are related

there is a trend that the more people there is in the family, the less is the average use

per person.

The water consumption for the hotels was very difficult to determine. Most managers

did not have a clear idea of how much water they used, and the answers they gave

were in many cases unreasonably high or low. Subsequently, an attempt was made to

verify the data obtained from the limited official records held at the Tanzanian

Ministry of Water (Integrated Planning Unit). This indicated that the hotel use could

be classified as:

• Low class hotels: 70 litres/person/day

• Medium class hotels: 200 litres/person/day

• High class hotels: 400 litres/person/day

The one hotel that had accurate water consumption data claimed to use an average of

between 200-240 litres of water per guest per day depending on the weather. This falls

well within the ranges set for the mainland and so these values seem equally

applicable to hotels on Zanzibar.

Water quality

During the interviews a total of 372 complaints or comments on the water quality

were received from the 193 interviewed persons. The major problem experienced by

the villagers and hotel owners is without any doubt brackish water in the wells.

Among the interviewed people 66% said that they found salinity to be a problem. The

complaints among the villagers were as follows:

14

Fig. 1. Experienced problems with water quality.

There were some differences between the villages in how the water quality was

perceived. For a more detailed description, see table 2.

Village System Salinity Illness Quantity Smell Supply Dirt

Jambiani S Pipe 3 7 10 3 3

Well 100 33 40 7

Jambiani N Pipe 7

Well 100 3 60

Paje Well 63 9 19

Bwejuu Well 94 6 6 3

Chwaka Pipe 100 7

Well 100 43 83

Dikoni Pipe 78 100

Well 100

Uroa Pipe 97

Well 100 34 7

Table 2: Problems noted by the villagers according to the interviews. Numbers

showing percent of interviewed people commenting on a specific issue.

15

As for the hotels, the answers were almost identical. The only noticeable exception

was illness, were the only complaints were from two hotels in Bwejuu who said they

experienced illness during the rainy season.

Usage patterns

The use of household water is shown in Figure 2.

Fig. 2. Use of water.

Other represents mainly water used for washing hands and feet before praying.

No significant differences between the villages was found.

As mentioned in the previous chapter, there are differences in quality and quantity of

water between wells. This fact forces people to use different wells for different

purposes. Especially water used for drinking has to be of good quality, and many

people use faraway wells for this.

A total for all villages shows that 75.7% of the villagers regularly uses more than one

well. The reason for this is in most cases high salinity in the nearest well, followed by

problems with quantity. There is also a typical pattern in how people use the different

wells. If the nearest well has problems with high salinity, this one is often used for

16

dishes and laundry and a well further away is used to collect water for cooking and

drinking.

Among them 61 % use two wells regularly because of reasons shown in Figure 3.

Fig. 3. Reasons for using two wells.

Three wells were regularly used by 15 %, for basically the same reasons.

Water sources

Wells

The traditional, and most common, source of freshwater in the villages is wells. Wells

are found in all villages in the region and are evenly distributed within the village.

They are hand-dug, and approximately 4-5 metres deep. The water is brought up from

the well with a bucket tied to a rope. This is the easiest and cheapest way to get water,

but heavy use within the village can cause saltwater-intrusion or draining the wells.

Pipe

In Jambiani, Chwaka and Uroa is however piped water the main source of potable

water. In these pipe-systems, water is pumped from a water-source, situated outside

the village, into a high storage-tank. The water is then distributed by self-pressure to,

and within, the village through the pipes. The pipes does most often end in public taps

in the village, but a few households has taps installed in their houses. The piped water

is supplied for free for the villagers. This way to supply water has fairly high

17

installation-costs and requires some degree of maintenance, but can supply water from

one or several good sources located away from the village.

In Jambiani, most hotels are connected to the pipe-system as well. The hotels that are

connected to a pipe-system have to pay a monthly water-fee to Zanzibar municipality.

The fee is based on expected water use (not the actual use), and is approximately 6000

TSh per month for a medium sized guesthouse.

Caves

Another source for water is groundwater collected from caves, located in the coral rag

west of the villages. The cave-water is suitable for piped-water, and is used as such in

Jambiani. The caves yields fair amounts of good quality water, and it is relatively easy

to extract it. The cave-water is however fairly susceptible to pollution, since both

people and animals very easily can enter the cave and contaminate the water.

The Ministry of Water, Construction, Energy, Lands and Environment (1995) have

pointed out three caves, including the one already in use by Jambiani, as very

promising for future water use in the Jambiani/Paje area.

Transport

If the available local watersources are not of acceptable standard, an option is to bring

in water from other places. Chwaka, where both the pipe-water and the well-water are

brackish, has an organised system for collecting drinking-water from Gendele, 3,5 km

west of Chwaka set up by a villagers. The collection of the water is done by car and

the villagers has to pay the local entrepreneur for this service. The price is 200 TSh

for the transport and 50 TSh for each 20 l bucket (according to the villagers). But

many people find this too expensive, so they continue to use the saline pipe-water for

drinking. In Uroa drinking-water is often collected by bicycle from the nearby village

of Marumbi, which has a pipe from an inland well.

Some of the hotels between Chwaka and Uroa also collects their water from places

further inland, since they don’t have any nearby well with acceptable water quality.

One hotel for instance collects its water from Ufufuma, 2 kilometres inland. The hotel

uses their own lorry to do this, and it takes 2500 litres per trip. The consumption of

water at the hotel is 2500 litres/day at high season and 1900 litres/day at low season

according to the manager. This does not include irrigation, but the amounts used for

irrigation are small.

One guesthouse in southern Jambiani is not connected to the village pipe-system, and

has no well on its premises that yields acceptable drinking-water. To solve the

drinking-water supply, the manager pays the locals to bring in buckets of water. For

this service he pays 150 TSh per bucket, three buckets a day during high season. This

adds up to 150*3*30 = 13.500 TSh per month.

Rainwater

During the rainy season rainwater is another source for household-water. Many

people said that they use rainwater only for dishes and laundry, since it is very soft

compared to the well-water. This reduces the amount of soap that has to be used, and

it also protects the colours of the clothing.

18

The rainwater is trapped as runoff from the roofs. Due to the climate with two distinct

rainy seasons and no rain in-between, the direct use of rainwater only accounts for a

minor fraction of the freshwater used throughout the year.

Desalinated Water

An efficient, but expensive, way to get freshwater is to use desalinators. In February

1997, this was only done by one hotel, a big Italian-owned hotel north of Bwejuu. The

desalination-plant consists of two desalinators, one in use, and one in stand-by. The

desalinators costed 100.000 USD each when they were purchased around early 1996.

Each desalinator contains 7 cartridge filters, which have to be replaced after three

days of use, due to the high content of salt and particles in the seawater. The

desalinators require a lot of energy. The hotel uses 500 litres of diesel every day for

producing electricity, but this also includes the electricity used for lights etc. The plant

yields a maximum of 5000 litres/hour of freshwater.

Village Sewage System

Most of the villagers use soak-pits as toilets, usually located inside or near their

house. Those who don’t have access to a pit uses the beach or the forest. The

measured levels of nutrients in the groundwater, which in some cases are very high,

indicates that the soak-pits in the villages probably leaks into the groundwater. The

sewage-leakage causes illness among those who uses it, since bacteria enters the

ground-water. This problem is biggest during the rainy season when groundwater-

movements are larger. This can also be seen in the interviews with many saying that

the problem with illness is bigger during rainy season.

The percentages of the households having a pit were as follows, according to the

interviews, which is shown in Table 3.

Village Percent of households using a soak-pit

Jambiani S 55

Jambiani N 63

Paje 100

Bwejuu 88

Chwaka 83

Uroa 33

Table 3. Distribution of soak-pits among the villages.

All hotels must have storage tanks for their sewage. These are of two types; soak-pits

or lined pits. All new-built hotels has to have lined pits. This type is lined with

concrete on the walls and bottom to prevent the sewage from leaking into the

surrounding ground. When the pit gets full the hotel calls Zanzibar municipality who

comes and collect its content. The collected sewage is then disposed on the main

rubbish dump in the outskirts of Zanzibar town. The hotels had to pay 20.000 TSh for

this service in March 1997 (according to Zanzibar municipality).

Many of the hotels on the coast were however built before the requirement to use

lined pits was introduced. They use the traditional soak-pit instead, with leaking floors

and walls, but they however often use two or three chambers for better cleaning. This

19

will however probably affect the groundwater anyway, since leakage still occurs, but

on a smaller scale.

One hotel north of Bwejuu has a septic tank to which enzymes are added regularly.

This should decompose all the sewage, and the tank don’t have to be emptied at all,

according to the hotel’s assistant manager. Since the hotel was not fully operating

during the visit, it was not possible to find out if the enzyme treatment was working.

The enzymes will however only decompose the carbon-chains, leaving the nutrients

unaffected.

Solid Waste Treatment

The solid waste generated in the villages is mainly household rubbish, which consists

of organic matter and, in an increasing amount for the past few years, of plastic bags.

Most people put the solid waste in a pit, and when the pit is full the content is set on

fire. Some people also put their waste on the beach, to be removed by the tide.

All of the hotels use a rubbish-pit, either on the hotel premises or in the forest west of

the village. None of the hotels uses source separation, but the two biggest hotels had

thoughts on introducing it in a near future. There is however no system for handling

the different fractions anywhere on the island today, all garbage that is collected by

Zanzibar municipality is thrown on the main rubbish dump. Burning of the waste in

the villages will probably not affect the groundwater.

Ground-water Chemistry

The results of the chemical analyses of groundwater samples showed major

differences between some wells for certain characteristics, and that most wells

exceeded the WHO standards for some quality parameters such as TDS and salinity.

Total Dissolved Solids

TDS represents the sum of inorganic substances like chlorides, bicarbonates,

sulphates, sodium, magnesium and calcium. Most of the TDS value obtained probably

comes from the CO3- in the bare rock or chlorides. The main effect Total Dissolved

Solids (TDS) is on taste. TDS levels below 600 mg/litre is generally considered to be

good-tasting, while levels above 1200 mg/litre are becoming increasingly unpalatable

(WHO, 1985). The WHO guideline is set to 1000 mg/litre based on taste

considerations.

Only a few of the investigated wells meets the guideline value, with minimum levels

in one well in Bwejuu being 682 mg/litre. No maximum value could be noted since

the equipment was not able to handle the high levels in most wells. Most well samples

had TDS values above the WHO standard of 600 mg/l.

Ammonia

For all nutrients the measured maximum values are in many cases above the

maximum levels recommended by Swedish authorities. Levels above 0,400 mg/litre

indicates that the water is affected by sewage. The limit for being considered

unsuitable for drinking is 1,0 mg/litre (Swedish National Food Administration, 2010).

At this level there is a risk for nitrite-bildning in the blood. In Chwaka the average

20

level was low, but there was one well with high levels. This well also had salinity-

levels low enough to make the water drinkable. All complaints on illness that was

noted in Chwaka during the interviews came from this well.

A comparison between the villages showed that the highest levels are found in

Bwejuu (Table 4).

21

Village Tide-level Average Std-dev Max Min

Jambiani S High 0,202 0,298 0,641 0,000

Low 0,068 0,0761 0,150 0,000

Jambiani N High 0,178 0,213 0,494 0,045

Low 0,208 0,262 0,589 0,026

Paje High 0,351 0,381 0,898 0,083

Low 0,341 0,345 0,832 0,033

Bwejuu High 1,362 1,63 3,805 0,437

Low 1,806 2,34 5,311 0,454

Chwaka High 0,490 0,652 1,454 0,044

Low 0,553 0,667 1,537 0,066

Uroa High 0,055 0,0520 0,109 0,000

Low 0,124 0,0882 0,218 0,044

Tabell 4: Ammonium concentrations in mg/l.

Phosphate

The maximum recommended concentration of phosphate in Sweden is 0,20 mg/l

(Swedish National Food Administration, 2010). This level is also an indication of

sewage intrusion. The mean values for the villages are shown in table 5 together with

max. and min. values. Single factor ANOVA-analysis showed no significant

differences in concentrations between wells in the villages. The inter-village-variation

was much greater than the intra-village-variation.

Village Tide-level Average Std-dev Max Min

Jambiani S High 0,777 0,62004 1,658 0,312

Low 0,979 0,673055 1,658 0,312

Jambiani N High 0,776 0,316683 1,117 0,351

Low 0,653 0,289383 0,981 0,385

Paje High 0,712 0,173075 0,937 0,520

Low 0,708 0,206605 0,953 0,456

Bwejuu High 0,893 0,419353 1,433 0,488

Low 0,909 0,354788 1,305 0,504

Chwaka High 2,215 2,994 6,701 0,589

Low 3,381 5,164 11,127 0,776

Uroa High 1,006 0,081649 1,117 0,929

Low 0,805 0,054728 0,844 0,742

Table 5: Phosphate concentrations in mg/l.

Nitrate

As in the case with ammonia, the highest levels of nitrate is found in Bwejuu (Table

6). Levels above 5,0 mg/l is an indication of influence from sewage (Swedish

National Food Administration, 2010). Water with levels above 10,0 mg/l should not

be given to children up to one years of age due to risk for metheamoglobinemia.

22

Village Tide-level Average Std-dev Max Min

Jambiani S High 0,342 0,292 0,674 0,072

Low 0,404 0,331 0,601 0,023

Jambiani N High 0,832 0,958 2,234 0,124

Low 0,389 0,380 0,752 0,043

Paje High 1,172 0,461 1,792 0,758

Low 1,063 0,567 1,647 0,295

Bwejuu High 3,216 3,918 9,090 1,162

Low 3,713 2,647 5,921 0,778

Chwaka High 1,659 2,777 5,798 0,020

Low 1,200 1,623 3,505 0,061

Uroa High 0,288 0,040 0,323 0,230

Low 0,257 0,139 0,369 0,101

Tabell 6: Nitrate concentrations in mg/l.

Salinity and Conductivity

Salinity and conductivity are closely related since conductivity is a measurement of

the number of free ions in the water and the salinity is the amount (weight) of

dissolved salts in the water. As noted in the interviews, salinity was considered to be

the major problem with the well-water according to both villagers and hotel-

managers. This view is strongly supported by both the salinity and conductivity

measurements, which shows high or very high levels in all villages.

The ANOVA analysis showed that Paje and Bwejuu had significantly lower levels of

salinity in the well-water than the other villages (see table 6). It might seem a bit

surprising that as much as 94% of the Bwejuu-people said salinity was a problem, but

only 63% in Paje, since there is no significant difference in salinity between Paje and

Bwejuu. The wells within Bwejuu has however levels between 0,7 and 1,8 PSU, and

the one well with 0,1 PSU is situated just outside the village itself. At the levels

measured within Bwejuu, the water has a distinct saline taste.

All wells in the area has at least some salinity and, as seen in table 7, in the most

extreme case up to 12,9 PSU was found (in Uroa). The differences between wells

within one village were large except in Paje where the range was between 0,3 and 0,8

PSU. No well showed any significant difference in salinity levels between high and

low tide. The tide-dependent difference was no more than 0,1 PSU. The pipe-water in

Jambiani, which is taken from a cave 2 km inland, had a salinity of 0,2 PSU.

Village Average Std-dev Max Min Number of wells

Jambiani S 3,046 1,851 6,8 1,3

Jambiani N 3,493 3,883 11,2 0,5

Paje 0,614 0,218 0,8 0,3

Bwejuu 0,928 0,528 1,8 0,1

Chwaka 3,745 2,640 8,1 0,6

Uroa 5,609 4,883 12,9 1,6

Tabell 7: Salinity concentrations in PSU.

23

WHO (1984) has set a guideline value for chloride (Cl-) to 250 mg/litre for drinking

water. This value is based on taste considerations, above this value the taste is

considered to be undesirable. The goal should however be 10% of this value to ensure

totally taste-free water. The Swedish authority gives an esthetic remark at 300

mg/litre, and a technical remark at 100 mg/litre (Swedish National Food

Administration, 2010). A technical remark means that there is a risk for corrosion in

the pipe-system. A chloride concentration of 250 mg Cl- per litre corresponds to 0,45

PSU (if the ion balance is considered to be the same as seawater with 55% of all ions

being Cl-)( Bydén et al., 1996). The conductivity values recorded from all wells

(Table 8) exceeds the Swedish health standards set to 0,40 mS/cm. in all cases

(Swedish National Food Administration, 2010).

Village Tide-level Max Min

Jambiani S High 11.6 2,69

Low 5,99 2,74

Jambiani N High 18,2 1,34

Low 18,7 1,34

Paje High 2,02 0,968

Low 2,01 0,960

Bwejuu High 3,60 0,682

Low 3,59 0,689

Chwaka High 14,17 1,54

Low 14,21 1,49

Uroa High 21,2 3,21

Low 21,1 3,15

Table 8: Conductivity in the wells, in mS/cm. The well with the highest value in

Jambiani S was dry at low tide.

DISCUSSION

As mentioned earlier, there are a range of items around the use and quality of

groundwater that may have a significant impact on its value as a resource. These

include salinity, access, sewage treatment and tourism. Further, access to potable

water can have a significant impact on water use patterns. In the present study the

main sources of potable water were from wells and pipes. These sources varied in

character but not so much in use.

Water Sources

The availability of water in the area is good today, but the amounts that are suitable

for drinking and cooking are not as large. To solve this situation the best thing would

be to use well-water for laundry and dishes, and piped water and, in the future,

desalinated water for drinking and cooking.

24

Well-water

Wells is the traditional way to get potable water in the villages. Increased use of

existing wells, and an increased use of latrine pits in the villages has however caused

an increased pollution and shortage of well-water in recent years. The levels of

nutrients are in many cases well above recommended levels, and saltwater intrusion is

making the water brackish. With a growing population it is not likely that the wells

will be able to provide enough water suitable for drinking and cooking in the near

future. The well-water will however remain useful for other things, like laundry and

dishes.

Piped Water

Piped water is probably the best way to solve the water supply in the future. The use

of pipes means that the water can be brought to the village from wells far away from

the coast, thereby minimising the risk for saltwater intrusion. The water could also be

evenly distributed within the village, or even to taps within the houses.

The main problem with the existing pipe-systems is to get the system to work

properly. The problem is in many cases lack of electricity, which is used to pump the

water from the source to the storage-tank. In Jambiani’s pipe-system the pumps also

has to be manually operated. This means that during night-time and holidays like

Ramadan, the access to pipe-water is limited. To avoid these problems, solar panels

and rechargeable batteries could be used to electrify the pumps, and automatic pumps

could be installed.

In case of a pump-breakdown, there should be stored water that could supply the

village for some time. The Tanzanian ministry of water recommends that the storage-

tanks that are used for pipe-systems should be able to store at least 50% of the total

daily demand (Integrated planning unit 1995). That means that the tank used for

Jambiani should hold at least 6237x35x0,5x0,001= 109,147 m3. The storage-tank that

is being used today holds 243 m3 so it would have to be replaced.

Cave-water

There are several natural caves filled with water in the coral rag east of the villages

These caves can be used as the water-source to supply the villages with water by a

pipe-system, as is the case today in Jambiani.

Used wisely, the caves represents a good source of water. Calculations by the

Ministry of water, construction, energy, lands and environment (1995) shows that an

average cave could produce 0,15*0,8*4*10E6 = 480.000 m3/year. This is enough to

supply 37.600 persons with water for a year, calculated on 35 l/p/d. This does

however mean that all of the potential cave-water is being used, which in the long run

can cause problems with salt intrusions. It might also have negative effects on the

surrounding ecosystems, since the water being used for human consumption otherwise

would have been used by plants and animals in the surroundings.

Transportation of Water

If no wells or piped water with good quality is available, transportation could be used

to get fresh-water. This is utilised by some hotels and, to a lesser extent, by some

25

villagers in Chwaka and Uroa as a way to collect water. It is however not a

sustainable long term solution. It is expensive and emissions from the transports have

negative environmental effects. The amounts that can be transported on one occasion

is comparatively small compared to the total need of a village. The only reason for

using transportation is as a short term solution if the water-sources available in or near

the village are of bad quality or lacking. In the long term, the hotel or village must in

such cases be supplied with water of good quality from i.e. a pipe-system.

Rainwater

Rain is a useful, but very seasonal, source for water. It is used throughout the area

when available, but it is in most cases used only for dishes and laundry, only rarely

for drinking and cooking.

The rain can however also have negative effects on the quality of the water in the

wells due to improper well-design. During heavy rains, the villages sometimes

become flooded, and all the dirt that has been stored on the streets during the year is

carried away by the flooding water. When the water sinks away, much of the

pollutants comes along and enters the groundwater. This is a problem especially

around some wells, were the ground-level near the well is lower than the surrounding

areas. This means that these wells can get severely polluted in connection with heavy

rains. This problem is easy to take care of, by making a concrete floor at ground-level

around the well.

Desalination of Sea-water

Desalination is used only to a minor extent today, but could be an important way to

get freshwater, at least for the medium-sized and large hotels. It has however some

major drawbacks. First of all, it is related to large costs. As mentioned earlier the price

for a desalinator is high, about 100.000 USD, and the maintenance has to be quite

extensive due to the high salinity in the sea-water. The desalinators also requires large

amounts of energy. The easiest way to supply this energy is with diesel-generators.

These generators are however noisy and causes emissions of i.e. CO2 and soot. It will

also be necessary to import the diesel, and transport it with lorries to the hotels.

The big advantage with desalinators is their large fresh-water production. The

amounts produced by the plant in use today, 5000 litres an hour, would be enough to

provide 8 medium class hotels with an average of 75 guests with water. If the costs

are shared between the hotels, it might be a possible solution.

A potential risk might be that the hotels starts using brackish well-water to produce

freshwater. This is obviously convenient for the hotel, since the desalination-process

does not have to be as extensive compared to using sea-water. The heavy use of the

well will however dramatically increase the salination-process in the aquifer. This

could have negative effects on both nearby aquifers as well as on surrounding

ecosystems.

To use desalination as a way to provide water for the villagers would be too costly.

The amounts of water required would be too big to be provided for with desalination

plants. If only water for drinking and cooking was desalinated, it would however be

possible to use desalination. For instance Jambiani uses 0,19*32,5*6237=38513

26

litres/day for cooking and drinking, and this corresponds to less than eight hours

(7h42min) of freshwater-production by a desalinator with the performance mentioned

above. The use of diesel to produce this water should be avoided, instead should solar

energy be used. Due to high costs and the big energy consumption, desalination is not

used on a larger scale anywhere in the third world today to provide rural villages with

fresh-water.

Water Quality

The chemical analysis supports the results from the interviews, i.e. that the quality of

the ground-water is not of an acceptable standard for household purposes. The levels

of nutrients strongly indicates sewage-influence and the salinity measurements shows

very high levels of salinity in the wells, probably due to saltwater-intrusion. Several of

the measured parameters are above the guideline values set by WHO. The high levels

of nutrients can in some cases be related to complaints of illness from a specific well.

Salinity

Both the high number of complaints on saline water and the chemical measurements

shows the salinity-levels in the well-water to be too high. According to the interviews,

the salinity is the most important factor determining which wells are being used, and

for what purposes. The results from the interviews clearly shows that salinity, more

than any other factor, affects how people use the wells.

The high levels of salinity in the wells is most likely due to saltwater intrusion from

the ocean. Once the saline water has entered an aquifer, it usually takes a long time

(10’s to 100’s of years) before the salinity comes back to the natural levels. This

process is done by natural recharge of fresh groundwater into the aquifer, and the

required time varies depending on precipitation and the local geology. Since efficient

recovery also requires that no or very little wells-water is drawn from the aquifer, it is

in most cases not easy to accomplish around villages.

The reasons for the measured differences in salinity between wells in the same village

and between villages are probably several but difficult to determine. For wells in the

same village, the age of the well and withdrawal rate are probably the most important.

The differences between villages might depend on differences in the local geology,

but exactly how this works in this area is not yet understood.

There are no acute medical problems from using saline drinking-water, since the taste

makes it undrinkable at unhealthy levels.

Smelly Well-water

The second biggest problem expressed during the interviews, next to salinity, was

smelly water. The reasons for smelly water is mainly due to decomposing organic

matter present in the water. The organic matter consists in many cases of things that

has fallen into the open well, either in connection with use of the well, or things fallen

in by accident, like leaves, small animals or wind-carried dust. Kids do also

deliberately put things into the wells.

27

Another reason that it smells could be that sewage has entered the well. A strong

indication that sewage is in fact present in the wells are the high values of ammonia,

nitrate and phosphate that was measured in many wells.

The problem with smell is very closely related to illness, another problem recognised

by the villagers, as decomposing organic matter and bacteria in the water plays an

important role in both cases.

The problem with dirt in the wells is recognised by the villagers, and many people

mentioned that the wells should be more protected by lids or other devices, to avoid

pollution. There were however not one single well in the villages with a lid, protecting

the water from miscellaneous debris. As noted earlier, nobody used another well for

collection of domestic water due to smelly water.

Illness

A total of 8,3% of the comments on water-quality noted during the interviews

concerned the fact that people was getting sick by their water. The number of

complaints on illness might however not correspond to the actual size of the problem,

partly because the interviews were conducted at the end of the dry season and people

might not have thought of illness as a problem at the moment. Another reason is that

some people don’t see any connection between drinking (bad) water and getting sick,

they think of illness as something caused by the Gods or just occurring without any

specific reason. This view was expressed by several of the interviewed people.

The reason for people getting ill by the well-water is basically that the water contains

pathogenic bacteria, which comes from several sources.One important source might

be sewage leaking from the latrine-pits into the wells. This view is supported by the

high nutrient levels measured in many wells, indicating a flow of nutrients and

pathogenic bacteria from the wells. Several people mentioned that the problem with

illness is bigger during the rainy season. Then is also the groundwater fluxes are

larger, flushing water from the surrounding ground into the wells. Something that

probably has a good, limiting effect on the spread of diseases is the fact that as much

as 8% of the household-water is being used for cleaning hands, feet and face before

praying. This cleaning is carried out several times a day.

The village with most complaints on illness was Chwaka, followed by the southern

part of Jambiani. There were no complaints at all on illness in Uroa. A strong

indication that sewage is responsible for the illness is found in Chwaka. All of the

complaints on illness from this village referred to the same well. The chemical

measurements showed that this well had the highest levels of ammonia in Chwaka,

but it is at the same time the only well in the village with a salinity-level low enough

to make the water drinkable. This forces people to use this well for drinking when the

piped water is not working, even though they know it may make them ill. As noted

earlier, people do not use another well because they find the nearest one might cause

illness.

Another problem, found in villages with pipe-water is that when the pipe is working,

very little or no water is drawn from the wells. This causes the conditions in the well

to be stagnant, with increased bacterial growth. When the piped supply fails and the

28

wells are being used again the water causes problems like diarrhoea among the

villagers.

Since the problem with illness is bigger during the rainy season, when water

movements are bigger, it is very likely that the pathogens come from nearby areas. A

very likely source is the soak-pits used for sewage. They probably get flushed, and the

water then enter the wells. To solve this problem, the wells and the soak-pits needs to

be separated.

Ammonia and Nitrate

The levels of ammonia and nitrate in the wells are, just like the levels of phosphate, in

many cases above the levels that indicates influence from sewage. This is most likely

due to the presence of latrine pits in the villages. The level for sewage-indication is

400 µg/litre for ammonia (Bydén et al, 1996; Swedish National Food Administration,

2010). This level could however also be caused by high iron- and humus-levels

(SLV). The level for being considered unhealthy for drinking is 1,0 mg/litre. At this

level there is a risk for nitrite-bildning.

In all villages except Bwejuu and Chwaka do the wells fulfil the level for safe

drinking (1,0 mg/litre). One well in Chwaka was above this level, and many villagers

complained that this well caused illness. Unfortunately, this is the only well in the

village with salinity levels low enough to make the water drinkable.

In Bwejuu one well showed as much as 5,3 mg/l. This level is extremely high,

indicating an ammonia-source nearby. Fortunately, the salinity-levels in this well

makes it impossible to use for drinking or cooking, so there were no complaints on

illness from using this well. The levels of ammonia in Jambiani’s pipe-system is

surprisingly high (1,4 mg/l), considering that the cave from where the water is fetched

is not affected by sewage from the village. The reason might be that the water-surface

in the cave, which is at ground-level, is very easy to access for animals, or for litter to

fall in.

The concentrations of nitrate shows the same pattern as ammonia. The village with

the highest concentrations is Bwejuu and the one with lowest concentrations is Uroa.

It is very likely that the ammonia and the nitrate comes from the same source.

There is no significant correlation between the ammonium-levels or nitrate-levels in

the wells and the number of sewage-pit users in the village. However, the lowest

levels of ammonia, as well as nitrate, is found in Uroa, which also has the lowest use

of latrine-pits.

Phosphate

The measured levels of phosphate does, just like ammonia, indicate influence from

sewage. The level for sewage-indication is 0,20 mg/l (Swedish National Food

Administration, 2010). This level was exceeded in all measured wells. The levels of

phosphate does however not show any significant differences between the villages.

The high concentrations of phosphates, together with the fact that they are the same

all over the area indicates that the source for phosphate might not be sewage, but

29

some other source. One reason could be influences from the surrounding geology on

the measured phosphate-levels.

There are no direct health-concerns associated with high phosphate levels, only the

indirect ones connected to sewage.

Used Amounts of Water

As noted was the average water use for villagers 32,5 litres per person and day for

personal use throughout the area. This can be compared with the recommendation

from the Tanzanian Ministry of Water (Integrated Planning Unit) that the minimum

use per person should be 30 litres per person per day for personal purposes.

To estimate the total per capita water consumption for a village, and not only the

household use, 25% should be added for use by small institutions and agriculture and

another 25% for waste and loss at the wells and in the pipes (Integrated Planning

Unit). This adds up to the total figure of 51 litres per person per day for total water use

in the studied area.

The amounts of water used for agriculture is however small in the area, and the water

that is being used for agriculture comes from wells near the fields, which are located a

few kilometres west of the villages.

These figures can also be compared with numbers from WHO which states that an

average of 20 - 40 litres of water is used per person and day for household purposes if

water is found within reasonable walking distance (Integrated Planning Unit). This

corresponds well with the results found by this study. As a comparison, the water use

in the USA is 400 litres/person/day (US EPA).

At the other extreme end, Drangert noted that in some villages in inland Tanzania

people survive on as little as five litres per person per day during the dry season.

The single most important factor determining the amount of water being used on in

the studied villages appears to be access to water, i.e. the distance to a well or pipe

providing useful water. The distance to the wells or taps are almost the same in all

villages, only the quality of the water found there differs. If water quality was prime,

larger differences would have been seen between the villages, for example Jambiani,

with good water quality uses the same amount of water as Uroa, which has much

poorer water quality. No differences can be seen between pipe-using villages and

well-using ones either. There is a trend that with increasing family-size, the average

water-consumption per person decreases. This supports the fact that access is the most

important factor for consumption-rate. It is only possible to carry a certain amount of

water to the house every day, due to the persons physical condition, time and other

factors. If the access was unlimited, with e.g. a tap in each house, the per-capita

consumption would probably increase.

A common problem mentioned during the interviews was the sometimes low quantity

of water in some wells. In the studied area the groundwater-level mostly follows the

sea-water-level. Since the maximum difference between high and low tide is 4,7

meters, many wells go dry, or at least very low watered during low tide. During heavy

use, or at the end of the day, some wells go dry as well, since the recharge can not

30

keep up with the withdrawal. These wells are usually possible to use again the next

day.

The number of wells in Paje has increased from 7-8 in the mid-eighties, to 30 in the

beginning of 1997. Several of the interviewed villagers claimed that they use more

water today than a few years ago, and that this is primarily due to the increased access

to water. On the other hand some people say that the increased access has not changed

their usage patterns. One can suspect that if all houses had running water installed, the

average consumption would increase.

The hotels often get the water from their own well, or from a pipe. The well-water is

usually pumped to a high storage-tank, and then distributed to the rooms by self-

pressure.

The fact that the hotels are sometimes located outside the villages probably has a

positive effect on the groundwater within the village, since the hotel and the village

might use different aquifers. There is, however, a risk that when one aquifer has been

drained, it will pull in water from neighbouring ones.

Sewage treatment

The way the sewage is treated today, i.e. the use of sewage-pits, does most probably

contribute to the high levels of nutrients found in the well-water.

The pits that are being used by the villagers are leaking into the surrounding ground,

also affecting the groundwater. To avoid this, the pits should be lined with concrete

on the walls and the floor, and emptied when they are full. This would mean that the

problem is avoided within the village itself, but the sewage still has to be treated

somewhere else. The sewage that is emptied from the hotel-pits today is just disposed

on the main city dump just outside Zanzibar town. This is an unacceptable solution,

with negative impacts on the area surrounding the dump. There is a risk for spreading

of diseases, as well as a risk for groundwater-contamination in the area. The smell is

not very pleasant either.

To build lined pits in all houses would be very costly, and if the cost for emptying

them is included, it is unlikely that the villagers would be able to afford it. If the

hotels are forced to pay a fairly high fee for emptying their pits, this could also cover

the cost for the villagers, in full or in parts.

Solid Waste treatment

The practice of burning the waste does probably not affect the groundwater. It would

however be desirable from an environmental point of view that no plastic materials

was burned. If the rubbish was collected and transported to a main rubbish dump, this

would solve the problem in the village, but creates an even larger problem at the main

dump. The water leaking from a big dump is usually very contaminated, posing a

threat to the local aquifer. If the organic waste could be decomposed and used as a

soil-improvement it would be beneficial for the agriculture.

31

The Future

This part will try to look into the future, to see what might happen in the area, and

what can be done.

The Tourists

As mentioned earlier the number of tourists visiting the island has increased

dramatically over the past ten years. This has increased the pressure on the water-

reserves significantly even though most tourists stays in guesthouses, using only a

small amount of water, and the season not beeing that long. If Jambiani is taken as an

example to calculate the amount of water used by tourists during high season,

compared to the use by local villagers, the following numbers is found.

• Number of hotel-beds: 319

• Average occupancy rate: 60% (high season)

• Average water consumption per tourist: 100 l/day (slightly above avg.

guesthouse standard)

• Total tourist water use per day: 319*0,6*100 = 19140 l/day

• Number of locals: 6237

• Average water use per local: approx. 35 l/day

• Total water use by locals: 218295 l/d

• Percent of water used by tourists: 8,1% during high season

Jambiani is a good example of how tourism can affect a local village. Tourism

developed at an early stage in Jambiani, and the village is still one of the most popular

destinations on Zanzibar. In January 1997 there were 12 guesthouses in the village,

with three more under construction. All of the guesthouses are located within the

village, and they use either piped water or their own wells (or in some case a public

well). This means that the water used by tourists directly affects the local water

supplies. The peak of the tourist season coincides with the drought-season, December

- February, which means that the biggest pressure from tourism is when the water-

reservoirs are at a minimum.

Since the tourists in this case represents only 3% of the total population during high

season, but use 8,1 % of the water-supplies, they put a larger per capita pressure on

the water-reservoirs than the villagers.

The construction of large high-class hotels can affect the groundwater in a much more

dramatic way. If they choose to use groundwater for all their needs, they will consume

big quantities. These hotels are however located outside the villages, and does thereby

not directly affect the quality and quantity of the water in the villages. As has been

mentioned earlier they can however cause indirect damages to the surrounding

aquifers.

The two high-class hotels north of Bwejuu has a total of 450 beds, the occupancy rate

is higher and the season longer than in the average guesthouse. This means that they

have a larger potential to severely damage the nearby watersources, not only affecting

the villagers but also themselves.

Assuming that their occupancy-rate is 80% during high season they use 0,8*400*450

= 144000 litres of water each day. This corresponds to 66 % of all the water used by a

32

village of Jambiani’s size. If a large-scale high-class tourism was about to be

developed on the island, it is clear that the question on watersupply had to be resolved

before any development begins.

With the expansion of hotels and guesthouses described by Integrated Planning Unit

(1993), the number of beds in the area would increase by 260%. This would of course

put an enormous pressure on the water supplies, as well as on sewage and solid waste

handling systems. It is difficult to see how this expansion would be possible at all.

The Villagers

With the current population-growth of 3%, the number of people living in this area

will be approximately 24000 in 2010. This is an population increase of 56% and also

means that the water consumption will have increased by 56% to 2010 as well. The

problems with quality and quantity of water that is experienced today will, if no

measures are taken, be even more severe by then. The population-increase is most

likely to continue, so something has to be done to improve the quality and quantity of

the water in the villages soon.

What To Do With the Water Supply?

The quality of the groundwater in the area is in many cases clearly not acceptable for

domestic use. The salinity-levels makes it unpalatable for drinking and cooking, and it

is also probably contaminated by sewage from latrine pits.

To avoid both saltwater-intrusion and contamination from the latrine pits, the water

should either be fetched from an inland well and supplied by pipes, or by desalination

of seawater. Desalination could be an interesting alternative if it is powered by solar

energy, and the resulting freshwater was only used for cooking and drinking. If any

other energy is used it would most likely be too costly and polluting. To provide the

water for all purposes from desalination would not only be unnecessary, but also

require quite an extensive desalination-process.

The best way to get freshwater to the villages is by building a pipe-system from one

or, preferably, several inland wells for each village. With sufficiently large storage-

tanks, well maintained pumps of good quality and well maintained pipes this is an

easy solution that will provide water of good quality to the villages. The pumps

should be run on solar energy to avoid problems with electrical supply.

The costs for the pipe-system should preferably to a large extent be paid for by the

tourists. The best way to do this is probably that for instance the water department

charges the hotels and guest-houses a monthly fee, which is then used to design and

maintain a proper water and sewage handling system throughout the rural villages.

The cost should be based on the actual use of water at the hotel. If there is a direct

connection between used amounts and the cost, the hotel owner will (hopefully) be

interested in lowering the water consumption and thereby his costs. The villagers

don’t have enough financial means to pay for this kind of service. They should

however contribute in some way to the building and maintenance of the water and

sewage. In this way they will feel that they are responsible for the supply, and

hopefully be careful how they use the water. It has to be guaranteed that no region is

33

discredited, all the hotels would have to contribute to this ”water-tax”, even those

located away from the villages. This solution will however probably run into political

trouble.

CONCLUSIONS

The measured levels of nutrients indicate that the groundwater is affected by sewage.

The levels in the wells water are in many cases well above the guidelines suggested

by WHO and The Swedish National Food Administration. The source of the

contamination is probably the sewage-pits used in all villages, to a varying extent.

All villages except Paje have problems with salinity in the wells. In Bwejuu the

problem was not too bad, but in the other villages everyone considered salinity to be a

major problem. The measurements of salinity confirmed this picture, with Paje and

Bwejuu having significantly lower salinity in the wells. The reason for the high

salinity levels in the wells is saltwater-intrusion from the ocean.

The usage-patterns are closely linked to the salinity in the wells. A high salinity

causes people to use different wells for different purposes, and to walk longer

distances to fetch drinking-water. If a large percent of the available water is used, the

risk for saltwater intrusion increases.

With both the population and tourism increasing, the pressure on the available water-

resources will be even greater in the future.

The best solution to this problem will be to fetch water from wells further inland.

Wells in the central parts of the island has lower risks of being affected by saltwater

intrusion and has the potential to yield larger flows of water. The use of desalination

is not a feasible solution. It gives large amounts of water, but the cost for the

desalinator and the energy to run it can not be carried by the locals or single

guesthouses. If the desalination-plants could be run on solar energy, and used by more

than one user it could be worth considering.

To request payment for the water-use from the villagers would not be a good idea.

They don’t have sufficient funds to pay for the water, and can not be accused for over-

use of the resources since they use just as much water as necessary to survive. If a

pipe-system with water from further inland is installed it has to be paid for in some

way. The simplest way to receive this money would be to charge the hotels and

guesthouses, and thereby indirectly the tourists. This would give the villagers good

water, and the tourists would contribute to the well-being of the islanders.

REFERENCES

Cunningham W P, Saigo B W (1995) Environmental Science, WCB Publishers,

Dubuque, USA.

Ministry of Water, Construction, Energy, Lands and Environment (1995) Review of

Design and Tender Documents and Supervision of Drilling and Construction of the

Zanzibar and Pemba Rural Water Supply, Part 1, Draft, 1995

34

Integrated Planning Unit (1993) Zanzibar Zoning Plan.

Drangert, J-O (1993) Who Cares About Water?, Linköping Studies in Arts and

Science, Linköping.

Parsons T R, Maita Y, Lalli C M (1984) A Manual of Chemical and Biological

Methods for Seawater Analysis, Pergamon Press, Great Britain.

Bydén S, Larsson A-M, Olsson M (1996) Mäta Vatten, Göteborgs Universitet

Swedish National Food Administration (2010) Dricksvattenkungörelsen, Statens

Livsmedelsverk, 1993:35, Stockholm 1993. www.slv.se/en-gb/

United Nations, New York (1987) Hydrogeological Map of Zanzibar and Pemba.

US EPA (2010) Environmental Protection Agency, www.epa.gov

35

ANNEX A QUESTIONAIRES

36

General village survey

Village

Head of village

Population

Main source of income

Other sources of income

Type and number of freshwater supplies Well

Pipe (from where?)

Cave water

Transport from other places

Rainwater

Other (specify)

Distance between high-tide and nearest (used) well

Any water-treating facilities in village, e.g. desalination

Any abandoned wells, and if so, why?

Number of guesthouses in/near village

Number of hotels in/near village

General comments on sewage treatment

General comments on solid waste treatment

Questionnaire for water usage patterns - Villagers

A1) Name of interviewed

A2) Name of head of family

A3) Family position

A4) Number of family members

B1) Which sources for household water do you use Well

Pipe

Transport from other places

Saltwater

Rainwater

Other (specify)

B2) What kind of water (well, pipe ..) do you use for different purposes, and

why? Type

Reason

Dishes

Laundry

Cooking

Drinking

Shower/washing

Other (specify)

B3) Do you regularly use water from more than one well, and if so, why?

B4) On average how much water do you use every day?

Dishes

Laundry

Cooking

Drinking

Shower/washing

Other (specify)

B5) Do you experience any of the following things as a problem with your water? Taste

Smell

Hardness

Salinity

Quantity

Access

Reliability

Causes illness

Other (specify)

B6) Has these problems increased or decreased in recent years?

B7) Who/what do you think has caused the problem Villagers

Hotels

Increased population

Farming

Over-use of water

Tourists

Other (specify)

B8) Has this increase/decrease of problem made you change your usage patterns,

and if so in what ways?

B9) How do you think these problems can be solved, and by whom?

B10) Do you contribute in kind or pay to use any of the watersources?

B11) What do you do with your wastewater? Sewage

Shower-water

Household-water

B12) What do you do with your solid waste?

B13) Any additional comments about freshwater?

Questionnaire for water usage patterns - Hotels/Guesthouses

A1) Name of hotel/guesthouse

A1) Name of interviewed

A2) Name of manager

A3) Number of beds

A4) Price per bed

A5) Number of guests in a week high season

low season

A4) Opened year

B1) Which sources for water do you use Well (own or village well?)

Pipe

Transport from other places

Saltwater

Rainwater

Other (specify)

B2) What kind of water (well, pipe ..) do you use for different purposes, and

why? Type

Reason

Household/guests

Irrigation

Pool

Other (specify)

B3) On average how much water do you use every day?

Dishes

Laundry

Cooking

Drinking

Shower/washing

Other (specify)

Total:

B5) Do you experience any of the following things as a problem with your water?

Taste

Smell

Hardness

Salinity

Quantity

Access

Reliability

Causes illness

Other (specify)

B6) Has these problems increased or decreased in recent years?

B7) Who/what do you think has caused the problem Villagers

Hotels

Increased population

Farming

Over-use of water

Tourists

Other (specify)

B8) Has this increase/decrease of problem made you change your usage patterns,

and if so in what ways?

B9) How do you think these problems can be solved, and by whom?

B10) Do you contribute in kind or pay to use any of the watersources?

B11) Do you treat your water in any way (e.g. desalination) before using it?

B11) What do you do with your wastewater?

Sewage

Shower-water

Household-water

B12) What do you do with your solid waste?

B13) Any additional comments about freshwater?