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CHAPTER 1

INTRODUCTION1.1 Water

Water is a common chemical substance that is essential for the survival

of all known forms of life. In typical usage, waterrefers only to its liquid form

or state, but the substance also has a solid state, ice, and a gaseous state, water

vapororsteam. About 1.460 petatonnes (Pt) (1021

kilograms) of water covers

71% of the Earth's surface, mostly in oceans and other large water bodies,

with 1.6% of water below ground in aquifers and 0.001% in the air as vapor,

clouds (formed of solid and liquid water particles suspended in air), and

precipitation. Saltwater oceans hold 97% of surface water, glaciers and polar

ice caps 2.4%, and other land surface water such as rivers, lakes and ponds

0.6%. Some of the Earth's water is contained within water towers, biologicalbodies, manufactured products, and food stores. Other water is trapped in ice

caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life

on land.

Water moves continually through a cycle of evaporation or

transpiration (evapotranspiration), precipitation, and runoff, usually reaching

the sea. Winds carry water vapor over land at the same rate as runoff into the

sea, about 36 Tt (1012kilograms) per year. Over land, evaporation and

transpiration contribute another 71 Tt per year to the precipitation of 107 Tt

per year over land. Clean, fresh drinking water is essential to human and other

life. However, in many parts of the worldespecially developing countries

there is a water crisis, and it is estimated that by 2025 more than half of the

world population will be facing water-based vulnerability. Water plays an

important role in the world economy, as it functions as a solvent for a wide

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variety of chemical substances and facilitates industrial cooling and

transportation. Approximately 70% of freshwater is consumed by agriculture.

Types of water

Water can appear in three states. Water takes many different forms on

Earth: water vapor and clouds in the sky; seawater and rarely icebergs in the

ocean; glaciers and rivers in the mountains; and aquifers in the ground.

Water can dissolve many different substances, giving it different tastes

and odors. In fact, humans and other animals have developed senses to be able

to evaluate thepotability of water, avoiding water that is too salty or putrid.

Humans also tend to prefer cold water rather than lukewarm, as cold water is

likely to contain fewer microbes. The taste advertised in spring water or

mineral water derives from the minerals dissolved in it, as pure H2O is

tasteless. As such, purity in spring and mineral water refers to purity from

toxins,pollutants, and microbes.

Different names are given to water's various forms:

according to state

o solid - ice

o liquid - water

o gaseous - water vapour

according to meteorology:

o hydrometeor

precipitation

precipitation according to moves precipitation according to state

vertical (falling)

precipitation

o rain

o freezing rain

liquid precipitation

o rain

o freezing rain

o drizzle

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o drizzle

o freezing drizzle

o snow

o snow pellets

o snow grains

o ice pellets

o frozen rain

o hail

o ice crystals

horizontal (seated)

precipitation

o dew

o hoarfrost

o atmospheric icing

o glaze ice

o freezing drizzle

o dew

solid precipitation

o snow

o snow pellets

o snow grains

o ice pellets

o frozen rain

o hail

o ice crystals

o hoarfrost

o atmospheric icing

o glaze ice

mixed precipitation

o in temperatures

around 0 C

o levitating particles

clouds

fog

BR (according to METAR)

o ascending particles (drifted by wind)

spindrift

stirred snow

according to occurrence

o groundwater

o meltwater

o meteoric water

o connate water

o fresh water

o surface water

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o mineral water contains much minerals

o brackish water

o dead water strange phenomenon which can occur when a layer

of fresh or brackish water rests on top of more dense salt water,

without the two layers mixing. It is dangerous for ship traveling.

o seawater

o brine

according to uses

o tap water

o bottled water

o drinking water or potable water useful for everyday drinking,

without fouling, it contains balanced minerals that are not

harmful to health (see below)

o Purified water, laboratory-grade, and analytical-grade or reagent-

grade water water which has been highly purified for specific

uses in science or engineering. Often broadly classified as Type

I, Type II, or Type III, this category of water includes, but is not

limited to the following:

distilled water

double distilled water

deionized water

according to other features

o soft water contains less minerals

o hard water from underground, contains more minerals

o distilled water, double distilled water, deionized water - contains

no minerals

o Water of crystallization water incorporated into crystalline

structures

o Hydrates water bound into other chemical substances

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o Heavy water made from heavy atoms of hydrogen - deuterium.

It is in nature in normal water in very low concentration. It was

used in construction of first nuclear reactors.

o tritiated water

according to microbiology

o drinking water

o wastewater

o stormwater or surface water

according to religion

o holy water

1.1.1Chemical and physical properties

Water

Water is a necessary solvent for all known life, and

an abundant compound on the earth's surface.

Information and properties

Common name Water

IUPAC name Oxidant

Alternative namesaqua, dehydrogenate monoxide,

hydrogen hydroxide,

Molecular formula H2O

CAS number 7732-18-5

Inch I Inch I=1/H2O/h1H2

Molar mass 18.0153 g/mol

Density and phase0.998 g/cm (liquid at 20 C, 1 atm)

0.917 g/cm (solid at 0 C, 1 atm)Melting point 0 C (273.15 K) (32 F)

Boiling point 99.974 C (373.124 K) (211.95 F)

Specific heat capacity4.184 J/(gK) (liquid at 20 C)

74.539 J/ (molK) (liquid at 25 C)

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1.1.2 Water (molecule)

Model of hydrogen bonds between molecules of water

Water is the chemical substance with chemical formula H2O: one molecule of

water has two hydrogen atoms covalently bonded to a single oxygen atom.

The major chemical and physical properties of water are:

Water is a tasteless, odorless liquid at ambient temperature and

pressure. The color of water and ice is, intrinsically, a very light blue

hue, although water appears colorless in small quantities. Ice also

appears colorless, and water vapor is essentially invisible as a gas.

Water is transparent, and thus aquatic plants can live within the water

because sunlight can reach them. Only strong UV light is slightly

absorbed.

Since oxygen has a higher electronegativity than hydrogen, water is a

polar molecule. The oxygen has a slight negative charge while thehydrogens have a slight positive charge giving the article a strong

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effective dipole moment. The interactions between the different dipoles

of each molecule cause a net attraction force associated with water's

high amount of surface tension.

Another very important force that causes the water molecules to stick to

one another is the hydrogen bond.

The boiling point of water (and all other liquids) is directly related to

the barometric pressure. For example, on the top of Mt. Everest water

boils at about 68 C (154 F), compared to 100 C (212 F) at sea level.

Conversely, water deep in the ocean near geothermal vents can reach

temperatures of hundreds of degrees and remain liquid.

Water sticks to itself. Water has a high surface tension caused by the

strong cohesion between water molecules because it is polar. The

apparent elasticity caused by surface tension drives the capillary waves.

Water also has high adhesion properties because of its polar nature.

Capillary action refers to the tendency of water to move up a narrow

tube against the force of gravity. This property is relied upon by all

vascular plants, such as trees.

Water is a very strong solvent, referred to as the universal solvent,

dissolving many types of substances. Substances that will mix well and

dissolve in water, e.g. salts, sugars, acids, alkalis, and some gases:

especially oxygen, carbon dioxide (carbonation), are known as

"hydrophilic" (water-loving) substances, while those that do not mix

well with water (e.g. fats and oils), are known as "hydrophobic" (water-

fearing) substances.

All the major components in cells (proteins, DNA andpolysaccharides)are also dissolved in water.

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Pure water has a low electrical conductivity, but this increases

significantly upon solvation of a small amount of ionic material such as

sodium chloride.

Water has the second highest specific heat capacity of any known

chemical compound, after ammonia, as well as a high heat of

vaporization (40.65 kJ mol1), both of which are a result of the

extensive hydrogen bonding between its molecules. These two unusual

properties allow water to moderate Earth's climate by buffering large

fluctuations in temperature.

The maximum density of water is at 3.98 C (39.16 F). Water becomes

even less dense upon freezing, expanding 9%. This causes an unusual

phenomenon: ice floats upon water, and so water organisms can live

inside a partly frozen pond because the water on the bottom has a

temperature of around 4 C (39 F).

1.1.3 Distribution of water in nature

A. Water in the Universe

Much of the universe's water may be produced as a byproduct of star

formation. When stars are born, their birth is accompanied by a strong

outward wind of gas and dust. When this outflow of material eventually

impacts the surrounding gas, the shock waves that are created compress and

heat the gas. The water observed is quickly produced in this warm dense gas.

Water has been detected in interstellar clouds within our galaxy, the

Milky Way. It is believed that water exists in abundance in other galaxies too,

because its components, hydrogen and oxygen, are among the most abundant

elements in the universe. Interstellar clouds eventually condense into solar

nebulae and solar systems, such as ours.

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Water vapour is present on:

Mercury - 3.4% in the atmosphere, and large amounts of water in

Mercury's exosphere

Venus - 0.002% in the atmosphere

Earth - trace in the atmosphere (varies with climate)

Mars - 0.03% in the atmosphere

Jupiter - 0.0004% in the atmosphere

Saturn - in ices only

Enceladus (moon of Saturn) - 91% in the atmosphere

Liquid water is present on:

Earth - 71% of surface

Moon - small amounts of water have been found (in 2008) in the inside

of volcanic pearls brought from Moon to Earth by the Apollo 15 crew

in 1971.

B .Water on Earth

Water covers 71% of the Earth's surface; the oceans contain 97.2% of

the Earth's water. The Antarctic ice sheet, which contains 90% of all fresh

water on Earth, is visible at the bottom. Condensed atmospheric water can be

seen as clouds, contributing to the Earth's albedo.

Hydrology is the study of the movement, distribution, and quality of water

throughout the Earth. The study of the distribution of water is hydrography.

The study of the distribution and movement of groundwater is hydrogeology,

of glaciers is glaciology, of inland waters is limnology and distribution of

oceans is oceanography. Ecological processes with hydrology are in focus of

ecohydrology.

The collective mass of water found on, under, and over the surface of a

planet is called hydrosphere. Earth's approximate water volume (the total

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water supply of the world) is 1 360 000 000 km (326 000 000 mi). Of this

volume:

1 320 000 000 km (316 900 000 mi or 97.2%) is in the oceans.

25 000 000 km (6 000 000 mi or 1.8%) is in glaciers, ice caps and ice

sheets.

13 000 000 km (3,000,000 mi or 0.9%) is groundwater.

250 000 km (60,000 mi or 0.02%) is fresh water in lakes, inland seas,

and rivers.

13 000 km (3,100 mi or 0.001%) is atmospheric water vapor at any

given time.

Groundwater and fresh water are useful or potentially useful to humans as

water resources.

Liquid water is found in bodies of water, such as an ocean, sea, lake, river,

stream, canal, pond, or puddle. The majority of water on Earth is sea water.

Water is also present in the atmosphere in solid, liquid, and vapor states. Italso exists as groundwater in aquifers.

The most important geological processes caused by water are: chemical

weathering, water erosion, water sediment transport and sedimentation,

mudflows, ice erosion and sedimentation by glacier.

1.1.4 Water cycle

The water cycle (known scientifically as the hydrologic cycle) refers to

the continuous exchange of water within the hydrosphere, between the

atmosphere, soil water, surface water, groundwater, and plants.

Water moves perpetually through each of these regions in the water cycle

consisting of following transfer processes:

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artificially in wells. This water storage is important, since clean, fresh water is

essential to human and other land-based life. In many parts of the world, it is

in short supply.

1.1.6 Water politics and water crisis

Water politics is politics affected by water and water resources.

Because of overpopulation, mass consumption, misuse, and water pollution,

the availability of drinking water per capita is inadequate and shrinking as of

the year 2006. For this reason, water is a strategic resource in the globe and an

important element in many political conflicts. It causes health impacts and

damage to biodiversity. The serious worldwide water situation is called water

crisis.

UNESCO's World Water Development Report (WWDR, 2003) from its

World Water Assessment Program indicates that, in the next 20 years, the

quantity of water available to everyone is predicted to decrease by 30%. 40%

of the world's inhabitants currently have insufficient fresh water for minimalhygiene. More than 2.2 million people died in 2000 from waterborne diseases

(related to the consumption of contaminated water) or drought. In 2004, the

UK charity WaterAid reported that a child dies every 15 seconds from easily

preventable water-related diseases; often this means lack of sewage disposal;

see toilet.

Rain Water

Harvesting

1.2 INTRODUCTION:

Water is nectar of life and life

cannot sustain without it. Ever

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increasing demands of water for domestic, irrigation as well as industrial

sectors have created water crisis worldwide. Ground water is the only

dependable source of water. Inferior quality of groundwater with high salinity,

fluoride and nitrate contents further limits the availability of fresh water

assets.

Depleting groundwater resources, water logging hazards, deep water

levels, higher degree of salinity, high fluoride and nitrate concentration,

industrial pollution etc. are the main ground water related areas of concern

which needs appropriate attention of management for Rain Water Harvesting

& Artificial Recharging.

Till about thirty years back, the areas around our homes and offices

used to be unpaved and the rain falling on these areas would percolate into

soil and remain there for being drawn through shallow open wells. With the

proliferation of flat complexes, these areas been covered, resulting in stopping

of percolation of rain water into the soil. But on the other hand the use of

ground water has risen immensely. With

Increase in the number of deep bore wells, the shallow wells started

drying up. The reason is that no sincere attempt was made to reestablish the

ground water table to its original level during monsoons.

As individuals, groups and communities, let us all wake up before it is

too late and only understand what rainwater harvesting is all about but also

implement measures to harvest rainwater in out homes, apartments and flat

complexes and put it into soil for our subsequent use.

In ancient days itself, people, especially Indians knew the methods ofconserving the rain water. There are evidences that even during the era of

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Harrappa civilization there was a very good system of collecting and storing

the rain water through channels. This has been observed in recent excavations

at Dholavira (Kacchh). During independence period people used to manage

water resources considering it as a part of nature which they praised as

Jaladevata, which was of course essential for their survival. This could be

observed from the rain water harvesting structures in low rainfall areas of

Rajasthan, harvesting springs in hilly areas and mountainous region and also

from the percolation tanks and ponds in southern India.

In Tamilnadu, The ancient people stored rainwater in public places

separately, one for drinking purpose and other for bathing and domestic use

which were called as Ooranies. They also formed percolation tanks or ponds

for the purpose of recharging irrigation to domestic wells. They periodically

used to clean the channels so as to get clean water throughout the year.

1.3 WHY RAIN WATER

HARVESTING?

Ground water plays a

critical role in the urban

environment. It has a significantcontribution in municipal,

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industrial and domestic water supply. Urbanization strongly affects ground

water recharge flow and quality thereby creating serious impact on urban

infrastructure that may lead to socio economic and environmental

degradation of the area. As urban dwellings go on increasing shrinkage of

open land leads to continuous decline in ground water levels in many areas.

It has therefore become imperative to promote rain water

harvesting and artificial recharge to augment ground water recharge.

Rain water harvesting is essential because :-

1. Surface water is adequate to meet our demand and we have to depend on

ground water.

2. Due to rapid urbanization infiltration of rain water into the sub soil has

decreased drastically and recharging of ground water has diminished.

3. Over exploitation of ground water resources has resulted in declined in

water levels in most part of the country.

4. To enhance availability of ground water at specific place and time.

5. To arrest sea water ingress.

6. To improve the water quality in aquifers.

7. To improve the vegetation cover.

8. To raise the water levels in wells & bore wells those are drying up.

9. To reduce power consumption.

1.4 COMPONENTS OF RAIN WATER HARVESTING:

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Rainwater harvesting is a technology used for collecting and storing rainwater

from rooftops, the land surface or rock catchments using simple techniques

such as jars and pots as well as more complex techniques such as underground

check dams. The techniques usually found in Asia and Africa arise from

practices employed by ancient civilizations within these regions and still serve

as a major source of drinking water supply in rural areas. Commonly used

systems are constructed of three principal components; namely, the catchment

area, the collection device, and the conveyance system.

A) Catchment Areas:

Rooftop catchments: In the most basic form of this technology,

rainwater is collected in simple vessels at the edge of the roof.

Variations on this basic approach include collection of rainwater in

gutters which drain to the collection vessel through down-pipes

constructed for this purpose, and/or the diversion of rainwater from the

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gutters to containers for settling particulates before being conveyed to

the storage container for the domestic use. As the rooftop is the main

catchment area, the amount and quality of rainwater collected depends

on the area and type of roofing material. Reasonably pure rainwater can

be collected from roofs constructed with galvanized corrugated iron,

aluminum or asbestos cement sheets, tiles and slates, although thatched

roofs tied with bamboo gutters and laid in proper slopes can produce

almost the same amount of runoff less expensively (Gould, 1992).

However, the bamboo roofs are least suitable because of possible health

hazards. Similarly, roofs with metallic paint or other coatings are not

recommended as they may impart tastes or color to the collected water.

Roof catchments should also be cleaned regularly to remove dust,

leaves and bird droppings so as to maintain the quality of the product

water (see figure 1).

Land surface catchments: Rainwater harvesting using ground or land

surface catchments areas is less complex way of collecting rainwater. It

involves improving runoff capacity of the land surface through various

techniques including collection of runoff with drain pipes and storage

of collected water. Compared to rooftop catchments techniques,

ground catchments techniques provide more opportunity for collecting

water from a larger surface area. By retaining the flows (including flood

flows) of small creeks and streams in small storage reservoirs (on

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surface or underground) created by low cost (e.g., earthen) dams, this

technology can meet water demands during dry periods. There is a

possibility of high rates of water loss due to infiltration into the ground,

and, because of the often marginal quality of the water collected, this

technique is mainly suitable for storing water for agricultural purposes.

Various techniques available for increasing the runoff within ground

catchment areas involve: i) clearing or altering vegetation cover, ii)

increasing the land slope with artificial ground cover, and iii) reducing

soil permeability by the soil compaction and application of chemicals .

Clearing or altering vegetation cover: Clearing vegetation from the

ground can increase surface runoff but also can induce more soil

erosion. Use of dense vegetation cover such as grass is usually

suggested as it helps to both maintain an high rate of runoff and

minimize soil erosion.

Increasing slope: Steeper slopes can allow rapid runoff of rainfall to the

collector. However, the rate of runoff has to be controlled to minimize

soil erosion from the catchment's field. Use of plastic sheets, asphalt or

tiles along with slope can further increase efficiency by reducing both

evaporative losses and soil erosion. The use of flat sheets of galvanized

iron with timber frames to prevent corrosion was recommended and

constructed in the State of Victoria, Australia, about 65 years ago

(Kenyon, 1929; cited in UNEP, 1982).

Soil compaction by physical means: This involves smoothing andcompacting of soil surface using equipment such as graders and rollers.

To increase the surface runoff and minimize soil erosion rates,

conservation bench terraces are constructed along a slope perpendicular

to runoff flow. The bench terraces are separated by the sloping

collectors and provision is made for distributing the runoff evenly

across the field strips as sheet flow. Excess flows are routed to a lowercollector and stored (UNEP, 1982).

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Soil compaction by chemical treatments: In addition to clearing,

shaping and compacting a catchments area, chemical applications with

such soil treatments as sodium can significantly reduce the soil

permeability. Use of aqueous solutions of a silicone-water repellent is

another technique for enhancing soil compaction technologies. Though

soil permeability can be reduced through chemical treatments, soil

compaction can induce greater rates of soil erosion and may be

expensive. Use of sodium-based chemicals may increase the salt

content in the collected water, which may not be suitable both for

drinking and irrigation purposes.

B) Collection Devices:

Storage tanks: Storage tanks for collecting rainwater harvested using

guttering may be either above or below the ground. Precautions

required in the use of storage tanks include provision of an adequate

enclosure to minimize contamination from human, animal or other

environmental contaminants, and a tight cover to prevent algal growth

and the breeding of mosquitos. Open containers are not recommended

for collecting water for drinking purposes. Various types of rainwater

storage facilities can be found in practice. Among them are cylindrical

ferrocement tanks and mortar jars. The ferrocement tank consists of a

lightly reinforced concrete base on which is erected a circular vertical

cylinder with a 10 mm steel base. This cylinder is further wrapped in

two layers of light wire mesh to form the frame of the tank. Mortar jars

are large jar shaped vessels constructed from wire reinforced mortar.

The storage capacity needed should be calculated to take into

consideration the length of any dry spells, the amount of rainfall, and

the per capita water consumption rate. In most of the Asian countries,

the winter months are dry, sometimes for weeks on end, and the annual

average rainfall can occur within just a few days. In such

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circumstances, the storage capacity should be large enough to cover the

demands of two to three weeks. For example, a three person household

should have a minimum capacity of 3 (Persons) x 90 (l) x 20 (days) = 5

400 l.

Rainfall water containers: As an alternative to storage tanks, battery

tanks (i.e., interconnected tanks) made of pottery, ferrocement, or

polyethylene may be suitable. The polyethylene tanks are compact but

have a large storage capacity (ca. 1 000 to 2 000 l), are easy to clean

and have many openings which can be fitted with fittings for

connecting pipes. In Asia, jars made of earthen materials or ferrocement

tanks are commonly used. During the 1980s, the use of rainwater

catchment technologies, especially roof catchment systems, expanded

rapidly in a number of regions, including Thailand where more than ten

million 2 m3 ferrocement rainwater jars were built and many tens of

thousands of larger ferrocement tanks were constructed between 1991

and 1993. Early problems with the jar design were quickly addressed by

including a metal cover using readily available, standard brass fixtures.

The immense success of the jar programmed springs from the fact that

the technology met a real need, was affordable, and invited community

participation. The programmed also captured the imagination and

support of not only the citizens, but also of government at both local

and national levels as well as community based organizations, small-

scale enterprises and donor agencies. The introduction and rapidpromotion of Bamboo reinforced tanks, however, was less successful

because the bamboo was attacked by termites, bacteria and fungus.

More than 50 000 tanks were built between 1986 and 1993 (mainly in

Thailand and Indonesia) before a number started to fail, and, by the late

1980s, the bamboo reinforced tank design, which had promised to

provide an excellent low-cost alternative to ferrocement tanks, had tobe abandoned.

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C) Conveyance Systems:

Conveyance systems are required to transfer the rainwater collected on

the rooftops to the storage tanks. This is usually accomplished by making

connections to one or more down-pipes connected to the rooftop gutters.

When selecting a conveyance system, consideration should be given to the

fact that, when it first starts to rain, dirt and debris from the rooftop and

gutters will be washed into the down-pipe. Thus, the relatively clean water

will only be available some time later in the storm. There are several possible

choices to selectively collect clean water for the storage tanks. The most

common is the down-pipe flap. With this flap it is possible to direct the firstflush of water flow through the down-pipe, while later rainfall is diverted into

a storage tank. When it starts to rain, the flap is left in the closed position,

directing water to the down-pipe, and, later, opened when relatively clean

water can be collected. A great disadvantage of using this type of conveyance

control system is the necessity to observe the runoff quality and manually

operate the flap. An alternative approach would be to automate the opening of

the flap as described below.

A funnel-shaped insert is integrated into the down-pipe system.

Because the upper edge of the funnel is not in direct contact with the sides of

the down-pipe, and a small gap exists between the down-pipe walls and the

funnel, water is free to flow both around the funnel and through the funnel.

When it first starts to rain, the volume of water passing down the pipe is

small, and the dirty water runs down the walls of the pipe, around the funnel

and is discharged to the ground as is normally the case with rainwater

guttering. However, as the rainfall continues, the volume of water increases

and *clean* water fills the down-pipe. At this higher volume, the funnel

collects the clean water and redirects it to a storage tank. The pipes used for

the collection of rainwater, wherever possible, should be made of plastic, PVC

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or other inert substance, as the pH of rainwater can be low (acidic) and could

cause corrosion, and mobilization of metals, in metal pipes.

In order to safely fill a rainwater storage tank, it is necessary to make

sure that excess water can overflow, and that blockages in the pipes or dirt in

the water do not cause damage or contamination of the water supply. The

design of the funnel system, with the drain-pipe being larger than the

rainwater tank feed-pipe, helps to ensure that the water supply is protected by

allowing excess water to bypass the storage tank. A modification of this

design is shown in Figure 5, which illustrates a simple overflow/bypass

system. In this system, it also is possible to fill the tank from a municipaldrinking water source, so that even during a prolonged drought the tank can

be kept full. Care should be taken, however, to ensure that rainwater does not

enter the drinking water distribution system.

1.5 Level of Involvement and Skills:

Various levels of governmental and community involvement in the

development of rainwater harvesting technologies in different parts of Asia

were noted. In Thailand and the Philippines, both governmental and

household-based initiatives played key roles in expanding the use of this

technology, especially in water scarce areas such as northeast Thailand.

Rainwater harvesting is an accepted freshwater augmentation

technology in Asia. While the bacteriological quality of rainwater collected

from ground catchments is poor, that from properly maintained rooftop

catchment systems, equipped with storage tanks having good covers and taps,

is generally suitable for drinking, and frequently meets WHO drinking water

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standards. Notwithstanding, such water generally is of higher quality than

most traditional, and many of improved, water sources found in the

developing world. Contrary to popular beliefs, rather than becoming stale with

extended storage, rainwater quality often improves as bacteria and pathogens

gradually die off (Wirojanagud et al., 1989). Rooftop catchment, rainwater

storage tanks can provide good quality water, clean enough for drinking, as

long as the rooftop is clean, impervious, and made from non-toxic materials

(lead paints and asbestos roofing materials should be avoided), and located

away from over-hanging trees since birds and animals in the trees may

defecate on the roof.

1.6 Specification:

Maintenance is generally limited to the annual cleaning of the tank and

regular inspection of the gutters and down-pipes. Maintenance typically

consists of the removal of dirt, leaves and other accumulated materials. Such

cleaning should take place annually before the start of the major rainfall

season. However, cracks in the storage tanks can create major problems and

should be repaired immediately. In the case of ground and rock catchments,

additional care is required to avoid damage and contamination by people and

animals, and proper fencing is required.

1.7 OBJECTIVES OF STUDY:

The Walchand College of Engg. has introduced subject Environmental

Studies in our syllabus .For these, we have to prepare project on

Environmental Studies.

As we know the heavy rain fall in Sangli area, caused the disaster of

floods for last two years. Simultaneously we can observe the scarcity of

water in nearby villages like Jat, Aatpadi etc. This made us to think over the

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Name of the site : ANANT MANGAL

Address : Anant Mangal, Near Khare Mangal Road,

Vishrambag, Sangli-416 415

2.2 THE METHODOLOGY OF RAIN WATER HARVESTING:

2.2.1. NEED OF WATER HARVESTING:

We had a bore-well before this water harvesting plants. It was 150 ft.

deep. There was very little water in this kind of well. Actually the water

obtained from this bore well was not sufficient throughout the year. We had to

think for some remedy and water harvesting was one of the best solutions.

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In the above mentioned site the type of rain water harvesting used is

ABSORPTION PIT METHOD.

2.2.2. BASIC REQUIREMENTS:

o PVC pipes

o Sintex tank or underground pit

o Sand filter

o Sloping slab

2.2.3. INSTALLATIONS:

Basically in this process rain water is collected. Many holes are

installed in the terrace. Through this holes water is collected by pipes in large

tank. These tanks are situated at ground level. Before collection it passes

through the SAND FILTER.

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Figure showing the installations of pipes to collect the roof top rain

water

Figure showing the Tank used for collection of water

2.2.4. PERCOLATION / ABSORPTION PIT METHOD:

A percolation tank or absorption tank is a hand made bore with the help

of augur and filled up with pebbles and river sand at the top. The depth of

these pits may vary from 4 to 8 meters, depending upon the nature of soil. If

the soil has more clay content, then the pit has to be extended downwards till

sandy stratum is reached. The diameter of these pits will be around 25

centimeters. A slit arrester is provided at the top of such pits.

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If this system has to be used in open space, then the diameter will be 1

meter and depth will be 1.5 meters. This pit will be filled with broken bricks

and pebbles. This construction is suitable for sandy or sub sandy regions. A

single unit consists of approximately 300 pits.

Figure showing the absorption pit. It is lined with bricks for

absorption purpose. All the collecting pipes open in this pit.

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Fig. Borewell Water Supply

Figure showing the Tank used for collection of water

3)

Name of the project : Rainwater harvesting

Name of the site : HOTEL PAI-PRAKASH

Address : Hotel Pai Prakash ,Vishrambag ,Sangli-416415

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2.3 METHODOLOGY OF STUDY:

The study for the present Project RAIN WATER HARVESTING is

carried out by OBSERVATION and DESK REFERENCE METHOD.

Rain Water Harvesting Structure

2.3.1 Type I:

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Ground Water Recharge calculations:

I. RWH structure size (1.5 x 1.5 x 2.0) mtrs.

1) Rainfall 2 cm/day

2) Roof top area 14m x 14m (45` x 45`)

3) Volume of rain water 4 cu.m

4)Total quantity of rainwater for 50,000 pits for

recharge.200000 cu.m or 44 Mgd

5) If 50 cm rainfall is expected during the

monsoon, then the quantity of recharge

25 x 44 Mgd i.e. 1100Mg

II. RWH structure size (1.0 x 1.0 x 1.5) mtrs.

1) Rainfall 2 cm/day

2) Roof top area 10m x 10m (30` x 30`)

3) Volume of rain water 2 cu.m

4)Total quantity of rainwater for 50,000 pits for

recharge.100000 cu.m or 22Mgd

5) If 50 cm rainfall is expected during the

monsoon, then the quantity of recharge

25 x 22Mgd i.e. 550Mg

The total quantity of recharge can be expected from 1.00 (L) Rain Water

Harvesting pits is 1100 Mg = 550Mg or 7500 ML.

The total area of Hyderabad is 165 Sq.Km.

The raise in ground water level will be 4.5 cm only from 1.00 (L) rain water

harvesting pits.

Hyderabad city is having 7.00 (L) households. If RWH structures are

constructed we can expect ground water recharge of 7 x 4.5 cm = 31.5 cm.

The roof top area for 7.00 (L) households at 12m x 12m will be 100 Sq.Km.

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If 100 mm of water i.e. 0.1m of water during the entire monsoon gets

absorbed into ground the quantity will be 1430 Mg and the raise in ground

water is by 3.9 cm on 165 Sq.Km area.

1.10.2 Type II:

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2.3.2 Type III:

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2.4 UTILISATION OF RAIN WATER AND RECHARGING OF

GROUND WATER THROUGH BOREWELL IN CASE OF

MULTISTORIED COMPLEXES

The residents of Multistoried Complexes can safely utilise Rain Water

for their Domestic requirements by way of filtering it and collecting into their

sump and also can recharge their borewells.

Quantity of rain water that can be collected from roof top from 2 cm

rain fall per day for domestic usage.

Rain Water Harvesting For Multistoried Complexes

Roof top

area in sqm.

Quantity

in cum.Litres Filter unit

Size of the

unit

Rate of

filteration

Time taken

for

discharge

- Small

Households1 cum 1,000

Type

Design

No.1

0.5m dia,

1.2m ht.20 lpm. 50 min.

- 100 Sqm. 2 cum 2,000 Type

Design

No.2

1.0m dia,

1.2m ht.

80 lpm.25 to 50

min.

- 150 Sqm 3 cum 3,000

- 200 Sqm 4 cum 4,000

- 500 Sqm 10 cum 10,000 Type

Design

No.3

1.2m dia,

1.2m ht.113 lpm.

90 to 180

min.- 1000 Sqm 20 cum 20,000

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Cost of Construction & Filtration Unit

2.5 OTHER METHODS USED FOR RAIN WATER

HARVESTING:

2.5.1 TRADITIONAL METHODS:

DescriptionType 1 (in

Rs.)

Type 2 (in

Rs.)

Type 3 (in

Rs.)

- Laying CC bed in 1:2:4 prop. For the size

shown in the diagram.300 600 700

- RCC rings 4 Nos. as per diagram 400 600 750

- Crushed 40mm metal (30cm thick)

400 800 1,000

- Crushed 20mm metal (15cm thick)

- Grit (Batana) 15cm thick

- Coarse sand (size 0.72mm to 1.0mm)

45cm thick.

- PVC 3" dia perforated pipe of hole size

0.6mm, 10cm c/c to be placed inside the

unit for collection of water and 1" dia and

1' pipe for backwash pumping.

100 200 250

- 3" dia PVC rain water carrying pipe upto

filteration unit and to sump and as well as

connecting to borewell casing pipe as per

site condition including labour charges

and fixing charges etc., (Approximately for

One floor).

1,000 1,000 1,000

- Other incidental charges and

transportation etc.300 300 300

Grand Total Rs. 2,500 3,500 4,000

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Traditional rain water harvesting was done on the surface bodies like

lakes, ponds, irrigation tanks, temple tanks, etc. This method is still practiced

in rural areas. In urban areas, due to loss of open space, rainwater has to

necessarily be harvested as ground water. Hence harvesting in such places

will necessarily will depend very much upon the nature of soil, either clay or

sandy etc. The below listed are the various kinds of traditional rainwater

harvesting methods.

Kul Irrigation Method.

Bamboo Method.

Kunds of Thar Desert.

Temple tanks of India.

2.5.2 MODERN METHODS:

The modern methods of rain water harvesting are categorized under two

classes; Artificial recharging and Rain water harvesting.

The Artificial recharging has again four types, namely

1. Absorption Pit method.

2. Absorption well method.

3. Well cum bore method.

4. Recharge trench cum injection well.

The rain water harvesting has types, namely

1. Individual houses

2. Group houses

These types are further classified into

1. Percolation pit method (already discussed).

2. Bore well with settlement tank.

3. Open well method with filler bed sump.

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4. Percolation pit with bore method.

2.5.3 PERCOLATION PIT CUM BOREWELL (FOR CLAY SOIL):

In areas where the soil is likely to be clayey up to 15 feet and more, it is

advisable to go for percolation well up to 10 ft. or 15 ft and a hand bore pit

within this well up to the depth of 10 ft. to 15 ft. from its bottom. A PVC pipe

of 6 inch diameter is inserted into bore fro entire length.

2.5.3 ARTIFICIAL RECHARGE THROUGH INJECTION WELL:

In this technique, 1 to 2 m wide & 2 to 3 m deep trench is excavated,

the length of which depend on the sight availability and volume of water to

be handled . An injection well of 100 to 150 mm diameter is constructed,

piercing through the layers of impermeable horizons to the potential aquifer

reaching about 3 to 5 meters below water level (1 to 10 m) from the bottom of

the trenches. Depending upon the volume of water to be injected, the number

of injection wells can be increased to enhance the recharging rate. A

schematic diagram is enclosed which is self explanatory.

2.5.4 RAINWATER HARVESTING IN GROUP HOUSES:

From Utilize open the well if any, within the complex to divert the

rainwater the terrace into it. If not, construct a well for this purpose. The

rainwater falling on the open space around the complex can be collected near

the gate providing a gutter with perforated lid. The collected water can be ledthrough necessary piping arrangements into a recharge well of 1 m diameter

and 5 m deep.

2.5.5 RAINWATER HARVESTING FROM ROOFTOP CATCHMENTS:

The rainwater harvesting performed also from the top of the roofs of the

buildings, bungalows, small houses. The application of an appropriaterainwater harvesting technology can make possible the utilization rainwater as

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a valuable and in many cases necessary water resource. Rainwater harvesting

has been practiced for more than 4,000 years and in most developed countries,

is becoming essential owing to the temporal and spatial variability of rainfall.

Rainwater harvesting is necessary in areas having significant rainfall but

lacking any kind of conventional, centralized government supply system.

Annual rainfall ranging from less than 500 to more than 1500 mm can

be found in most Latin American countries and the Caribbean. Very

frequently most of the rain falls during a few months of the year, with little or

no precipitation during the remaining months.

For more than three centuries, rooftop catchments and cistern storage

have been the basis of domestic water supply on may small islands in the

Caribbean. During World War II, several airfields were also turned into

catchments. Although the use of rooftop catchments systems has declined in

some countries, it is estimated that more than 5,00,000 people in the

Caribbean islands depend at least in part on such supplies.

2.5.6 Technical Description:

A rainwater harvesting system consists of three basic elements: a

collection area, a conveyance system and storage facilities. The collection

area in most cases is the roof of a house or a building. The effective roof area

and the material used in constructing the roof influence the efficiency of

collection and the water quality.

Following questions need to be considered in areas where a rainwater

cistern system project is being considered, to establish whether or not

rainwater catchment warrants further investigation:

- Is there a real need for an improved water supply?- Are present water supplies either distant or contaminated, or both?

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- Do suitable roofs and /or other catchment surfaces exist in the

community?

- Does rainfall exceed 400 mm per year Does an aim proved water supply

figure prominently in the communitys list of development priorities

If the answers to these five questions are yes, it is clear indication that

rainwater collection might be feasible water supply option. Further questions,

however, need to be considered:

What alternative water sources are available in the community and how

do these compare with the rooftop catchments system?

2.6 EXTENT OF USE:

Rainwater harvesting is used extensively in Latin America and

Caribbean, mainly for domestic water supply and in some cases, for

agriculture. In Brazil and Argentina, rainwater harvesting is used in semiarid

regions. In Central American countries like Honduras, Costa Rica, Guatemala

and EI Salvador, rainwater harvesting using rooftop catchments is used

extensively in rural areas.

The Turks & Caicos Islands have a number of government-built, public

rainfall catchment systems. Government regulations make it mandatory that

all developers construct a water cistern large enough to store 400 l/m2 of roof

area.

Rooftop & artificially constructed catchments, such as the one at the

former United States naval base on Eleuthera and the other at common place

in the Bahamas. One settlements (whale Cay) has a piped distribution system

based on water captured from rooftops. On New Providence, most of the older

houses & stores in cisterns with average capacities of 70,000 l. Industries also

use rooftop rainwater, & a preliminary assessment has been made of using

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2. Climate of area

3. Installation of tank either above/below the ground

4. Purpose of harvested water (household or irrigation?).

2.8 ADVANTAGES OF RAIN WATER HARVESTING:-

Rainwater harvesting provides a source of water at the point where it is

needed. It is owner operated & managed.

It provides an essential reserve in times of emergency and/or breakdown

of public water supply systems, particularly in natural disasters.

The construction of a roof top rain water catchments systems is simple,

and local people can easily be trained to built one, minimizing its cost.

The technology is flexible. The systems can be built to meet almost any

requirements. Poor households can start with a single small tank and add

more when they can afford.

It can improve the engineering of building foundation when cisterns are

built as part of the substructure of the buildings, as in the case of

mandatory citterns.

The physical and chemical properties of rainwater may be superior to

those of groundwater or surface waters that may have been subjected to

pollution, sometimes by unknown sources.

Running costs are low.

Construction, operation, and maintenance are not labor-intensive.

2.9 DISADVANTAGES:-

The sources of rainfall harvesting depend upon the frequency and amount

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of rainfall; therefore, it is not a dependable water source in times of dry

weather or prolonged drought.

Low storage capacities will limit rainwater harvesting so that the system

may not able to provide water in a low rainfall period

Leakage from casters can cause the deterioration of load bearing slopes.

Cisterns and tanks can be unsafe for small children if proper access

protection is not provided.

Possible contamination of water may result from animal wasters and

vegetable matter.

Rainfall harvesting systems may reduce revenues to public utilities.

Rainfall harvesting systems increases construction costs and may have an

adverse effect; on home ownership. Systems may add 30% to 40% to the

cost of a building.

2.10 RESULT:-

The rain water harvesting has helped a lot in increasing the ground

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water table in this area. The bore wells are able to supply more amount of

water than that of three years ago. As the entire rainwater falling on the roof is

percolated in soil, it has also reduced the health problems due to mosquitoes

in this area. The water collected in tanks can be used to water the gardens and

for other domestic purposes so as to avoid the wastage of fresh water. Thus

the rain water harvesting project installed over here is proven to be

economical.

CHAPTER 3

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SUMMARY & CONCLUSION

3.1 FURTHER DEVOLOPMENT OF THE TECHNOLOGY:-

There is a need for the water quality aspects of rainwater harvesting to

be better addressed. this might come about through:

Development of first-flush bypass devices that are more effective and

easier to maintain and operate than those currently available.

Greater involvement of the public health department in the monitoring of

water quality.

Monitoring the quality of construction at the time of building. Other

development needs include.

Provision of assistance from governmental sources to both government

and private - sector- supplied water, with emphasis on the savings to be

achieved on water bills.

Development of new materials to lower the cost of storage.

Preparation of guidance materials (including sizing requirements) for

inclusion of rainwater harvesting in multi-sourced water resources

management environment

3.2 CONCLUSION:-

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We have to restore to long term measures in harvesting the rainwater

due to growing demand, which is chain reaction of population explosion. It is

our humble request to all the people to try to restore every drop falling from

the sky.

Each and every drop of water falling from the sky must be saved and

reutilized so as to minimize the water shortage during the dry seasons. Rain

water should be collected and either stored or allowed to percolate so as to

meet the water needs of the upcoming generation.

CHAPTER 4

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BIBLIOGRAPHY

BIBILOGRAPHY

1. A book on Environmental studies published by Shivaji University,

Kolhapur.

2. Comprehensive Environmental studies by J.P. Sharma

3. Water and Basic Environmental Technology by Sunit Gupta

4. www.wikimapia.in

5. www.rainwaterharvesting.org

6. www.aboutrainwaterharvesting.com

7. www.rainwaterclub.org

8. www.villageearth.org

water harvesting final report

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