Domestic Water Consumption in Chennai Findings of A Sample Survey*

A.Vaidyanathan** J Saravanan***

Introduction

Most discussions of urban water supply focus on the ability of the public system to provide certain norms in terms of per capita supply, and various technical, managerial and financial problems of its operation. However, the public system is not the only source of supply. Some years back, a large scale survey of Chennai Corporation showed that the total volume consumed per capita was considerably less than the norm of 120 lpcd considered necessary in metropolitan areas and that public sources contributed less than half of the total consumption. That groundwater extracted by privately owned wells and bore wells was the main private source and that groundwater levels in the city have been falling progressively was known in a general way. But no hard data were available. The present survey is designed to get a fuller and more detailed assessment of systematic estimates of the overall levels and patterns of water use, the relative contributions of different public and private sources of supply as well as the behaviour of the groundwater table.

* The survey is part of the Centre for Science and Environment’s on-going work on the current status, problems and prospects of water supply in urban areas of the country. ** Emeritus Professor, Madras Institute of Development Studies, Chennai*** Former Centre for Science and Environment staff

Scope and Design of Survey

The Survey, conducted during December 2003 and January 2004, was limited to households within the limits of the Chennai Corporation. Commercial and industrial establishments and other public and private institutions were not covered. A representative sample of 1510 households was interviewed for collecting data. The 155 wards in the city were grouped into three broad categories according to the availability and reach of the public system based on assessment by Metro Water officials. Wards within each of these categories were further categorized into upper, middle and low-income neighbourhoods. Though this was done in consultation with several knowledgeable persons, it is necessarily impressionistic. We thus had nine categories of wards.

A stratified random sampling procedure was used to select a total of 1510 households, the number that seemed feasible within the constraints of time and resources available. The number of sample households to be selected in the 9 strata was allocated in proportion to the total number of households in each of them (obtained from the 1991 census; Since the ward wise population of 2001 census was not available at the time of study). It was further decided that households to be surveyed should be selected from a randomly selected sample of the streets within each sample ward and that at least randomly selected 10 households should be interviewed from each sample street. The number of sample wards in each stratum and the number of sample streets in each sample ward was determined on this basis. The sample wards and sample streets within each of them were chosen through random selection. A total of 1510 sample households in 151 streets located in 31 wards were covered by the survey. Details are given in the annexure 1. The location of the sample wards is shown in the accompanying map.

The survey schedule (see annexure 2) was designed to elicit information of household characteristics, the sources on which they normally depended for different uses, and the actual quantity they obtained from different sources during the day prior to the interview, particulars of storage tanks and sumps, purchase of water from metro tankers and private tankers, costs of getting water from different sources, the characteristics of wells/bore-wells (including the time of their construction, deepening and current and original depth and power source), and implementation of rainwater harvesting.

The interviews were conducted from late December 2003 through January 2004 by postgraduate students in social work from the Madras Christian College. Their field work was closely supervised and the filled in schedules scrutinized by Prof. Annadurai and Dr.Mirium Samuel, head of that department and Sri J Saravanan. In several cases investigators had to revisit the households to fill in gaps and get clarifications. An effort was made to get the relevant information from the head of households as well as female members who are far better informed about domestic water use. Most were willing to answer all the questions and give information.

However some of the questions and in some cases the instructions to field investigators were not framed clearly. For instance, the questions relating to quantum of water used from different sources did not specify the contribution of private tankers. The treatment of multiple occupancy households and flats raised some difficulties in estimating overall consumption and use because the schedule did not include questions on the number of households in such cases. Information

relating to water supply and dependence on different sources under ‘usual’ or ‘normal’ conditions and in the current situation is difficult to interpret because of some ambiguities in the questions.

These problems notwithstanding, thanks to the cooperation of the informants and the effort put in by the field investigators, the Survey has provided much valuable data to piece together a picture of the core aspects of sources and use of water, groundwater exploitation and rainwater harvesting among the sample households, as well as the variations in these features between different parts of the city and across different income groups. That the estimates of total consumption by sources and uses based on the survey data are broadly corroborated by estimates from other independent sources.

Estimates of quantities consumed by purpose and source are based on informants’ recollection of the number of pots and buckets used the day before the interview. These containers are generally, but not always, of two or three standard sizes. Moreover, the information obtained is based not on actual observation but on recollection of the respondents. The data are therefore necessarily approximate. Nevertheless, a comparison of the estimates of total per capita consumption from the public system with the Metro Water figures of the quantity supplied during the survey period suggests that the survey estimates are in the right ball park. Estimates of per capita consumption for individual uses (except perhaps toilets) also seem plausible.

Characteristics of sample households

The location of the 31 sampled wards can be seen from map 1. Table-1 gives their distribution according to original stratification by conditions of public supply and a notional assessment of relative prosperity based on the proportion of households living in slums. The location of the sample wards is shown in Map 1.

Table 1: Distribution of sample wards by extent of public supply and average living conditions

UPPER INCOME

MIDDLE INCOME

LOWER INCOME

GOOD SUPPLY 5 5 3MEDIUM SUPPLY 5 4 2POOR SUPPLY 3 2 2

The sample households had a total of 6176 members of whom roughly a third (2022) were children. More than three fourth of the heads of sample households report having secondary or higher level education. About a third report themselves as self-employed; a little less than half as having regular employment. About an eighth of them are pensioners. The proportion reporting casual wage employment is surprisingly small at 6 per cent.

Table – 2: Education and Occupation of the sample house hold headTotal members Education of house hold headAdult Children Non literate Elementary Secondary Diploma Degree6176 2022 110 216 410 86 688

Table – 3: Occupation of the sample house hold headOccupation of house hold headSelf Employed

Regular Employee-Organised Sector

Regular Employee-Unorganised Sector

Casual Wage Employment

Pensioner

521 442 227 129 191

Of the total surveyed house holds about 42% fall in the income group of less than Rs. 5000 per month, and about 7 percent more than Rs.15000 per month. About 63 percent of the sample households live in their own houses and the rest in rented accommodation. The sample households are divided more or less equally between single occupancy homes and multiple occupancy houses. About 18 percent of the households live in flats. The relative importance of owned housing and single occupancy also varies with income. As may be expected, the proportion of households living in own houses and in single occupancy residences increases with income (Table 4).

Table 4: Characteristics of House holds with different income levels Household income group in Rs.

No. of households

Living in own house

Living in single occupancy

<5K 600 309 2455K – 10 K 397 262 21010K – 15 K 333 215 277>15 K 97 83 72All reporting households 1427 58 118Total sample households 1510 927 922

Note: some sample households did not provide the information. their number under each characteristic is indicated as non-reporting Dependence on sources

The sources of supply as reported by the sample households, and the number of households reporting different sources are presented in table 5. Roughly 55 percent of the sample households have direct metro water connections; 64 percent report accessing fixed tanks, taps and hand pumps provided by Metro Water; and about 11 percent metro tankers. Nearly two thirds of sample households have their own wells or bore wells. Access through others’ wells and private tankers is reported by less than 5 percent each of the total households. The fact that the number of sources is nearly double the number of households shows that Chennaities depend on multiple sources for their water supply.

Table – 5: Number of households reporting different means of access to water supply Sources Sample householdsPublic Direct in-house Outside tap/hp Storage tank Metro tanker

834417450178

Own well 1000 Others well 50 Community well 5Private tanker 45Total 2979

This is further highlighted by table 6, which gives the situation at the time of the survey in respect of sources from which households draw their supplies. Only 40 percent of sample households report using a single source mostly wells (407 households), followed by metro tankers (178) and private tankers (45).

Of those who report multiple sources, by far the largest number supplement own well with other sources; a sizeable number use metro water tankers along with other sources (again mostly wells)The large majority of households depend on a single source for each purpose, but different sources for different purposes. A sizeable proportion (ranging from one eighths in the case of toilets to one fifth for drinking) uses two sources. A much smaller number of respondents use the three sources. Only 40 percent of sample households report using a single source mostly wells (407 households), followed by metro tankers (178) and private tankers (45). Of those who report multiple sources, by far the largest number supplement own well with other sources; a sizeable number use metro water tankers along with other sources (again mostly wells) (Table 6)

Table 6: Dependence of sample households on multiple sourcesSources HomesOwn Well and Metro tanker 462Own well and Other well 23Own well and Community well 2Own well and Private tanker 31Metro tanker and Other well 116Metro tanker and Community well 73Metro tanker and Private tanker 18Other well and Community well 1Own well, Metro tanker & Other well 9Own well, Metro & Private tanker 6Metro & Private tanker, Other well 1

The pattern of source dependence varies with income. Taking all uses together, (see Table 8) the proportion of sample households reporting dependence on wells as the sole source increases progressively from about 11 percent in the lowest to more than half in the highest income group; dependence on metro tankers is inversely related to income: the proportion being roughly a sixth of lowest income group and practically zero in the 15+K group; on the other hand, dependence on private tankers as the sole source is negligible in low income groups and is relatively high (12 percent) in the highest. The incidence of multiple sources does not show a clear pattern.

Table 7: No. of sample households by income group reporting use from various sources Own well Met

tankerOther well

Comm. Well

Private tanker

Multiple sources

Total Homes

5k 65 106 44 5 2 273 6005k-10k 101 45 5 0 3 39 39710k-15k 109 17 1 0 27 159 33315k-20k 51 0 0 0 12 25 97105 households in the 5k group, 204 households in the 5k-10k group, 20households in the 10k-15k group and 5households in the >15k group haven’t responded

This is further highlighted by table 8, which gives the number of households reporting use of different sources for different purposes. The following features are noteworthy:

- Public supply from tap inside and outside the house is used for practically all purposes more or less with equal frequency.- Fixed tanks and tankers of the public system are used for drinking and cooking far more frequently than for other uses - Wells (own or others’) are used mainly for washing, bathing and toilets.- Private tanker supply is used by sizeable number of households in all uses, but more so

for purposes other than drinking.- It is noteworthy that nearly a fourth of the households use bottled water for drinking

and about 8 percent for cooking.Table 8: Number of sample households using different source for different uses Uses

Sources Drinking Cooking Washing Bathing Toilet OtherTotal Households

Public in- house 270 271 204 209 187 28 1169Public outside 49 44 50 50 48 26 267Public handpump/tap 143 149 150 122 118 29 711Public fixed tank 176 160 59 62 52 60 569Public tanker 558 549 228 216 166 28 1745Own well 153 325 804 808 811 147 3048Others well 17 31 60 63 60 28 259Community well/handpump 5 9 86 85 85 14 284Private tanker 41 91 97 110 88 37 464Bottled water 424 114 1 0 0 0 539Total households 1836 1743 1739 1725 1615 397 9055

The survey data further show that households with less than Rs 5000 per month depend on public supply both in-house and outside for all the daily uses. Water from public tankers and from fixed tanks is used mainly for drinking and cooking purposes. Water from private wells is used mainly for washing and bathing purposes. The dependence of bottled water is very low in this group. This pattern is noticed in the middle groups as well except that a larger proportion of them depend on bottled water for drinking. Those in the highest income group depend on public system to a much smaller extent than others. This group depends more on own wells and private tankers for all uses except for drinking. The dependence on bottled water is quite high for drinking and cooking in this group.

Storage devices

Chennai households combine use of multiple sources with the use of overhead tanks and sumps to store water. Nearly 55 percent of sample households report having overhead tanks (with capacities ranging from less than 500 litres to over 8000 litres) and somewhat over a fifth have sumps Capacities ranging between less than 1000 litres to over 10,000 litres). The proportion of households reporting OHTs and Sumps is relatively higher among single occupancy households. The incidence of these storage facilities is relatively limited in the case of households in the lowest income group (where about 28 percent of households report OHT and barely 7 percent sumps) while it is practically universal in the highest income group (88 percent with OHTs and 75 percent with Sumps)

Table 9: Distribution of OHTsand Sumps by income groups

Total households

No. of homes with OHT

No. of homes with Sump

5K 600 171 405K-10K 397 289 7810K-15K 333 300 14215K-20K 97 86 73All 1427 846 333 About 83 households of the total sample of 1510 haven’t reported on the monthly income

Patterns of water consumption

Per capita useAverage per capita daily domestic water consumption of sample households during the survey period (in December 03-January 04) ranged from less than 25 litres to more than 125 litres. About one third of the households reported consumption rate between 25 and 50 lpcd and around 39 percent between50 and 75 lpcd. The range of variation is considerably reduced if we adjust for differences in the composition of households in terms of the proportion of adults and children, Assuming that two children are equivalent to one adult unit,

Table – 10: Frequency distribution of sample house holds by level of per capita daily use Level of daily use in litres per day

<25 25-50 50-75 75-100 100-125 >125 AllPer capita No of hhs

59 475 599227 113 37 1510

Per Adult Unit No. of hhs

34 366 539327 172 72 1510

Distribution by useThe major part (nearly two thirds) is used for cooking and washing; and a little over a sixth for toilets. The average use for drinking is 4 lpcd and for cooking 4.9 lpcd. Per capita usage both overall and for different purposes varies: the coefficient of variation– which is a measure of the degree of variation – is around 30 percent for total usage; the variation is much higher than average in the usage for washing and toilet; about the same as average for drinking and the least for bathing. Table 11 : Mean Per capita consumption in litres per day for different uses*

Drinking Cooking Washing Bathing Toilet Others TotalMean 4.0 4.9 22.6 15.1 10.3 1.1 58.1Standard Deviation 1.2 1.1 12.2 2.9 4.0 1.8 17.3cv 0.30 0.23 0.54 0.19 0.39 1.55 0.30

Distribution by source of supplyMetrowater accounts for about 35 percent of the reported consumption of sample households, the major part of it from tanks, pumps and taps outside the side the house as well as metro tankers. The major part is from wells – about half the total use is accounted by own wells and the balance by others’wells.(Table 12)

Table – 12 : Source wise per capita consumption of sample households* Source Households reporting

number and % of sample household

Consumption lpcd % of total consumers

Metro Inhouse 321 21 6.8 13Metro outside 828 55 11.8 22Own Well 821 54 26.5 50Other well 351 23 6.3 l1.2Bottled water 389 25 0.8 1.5

*Excludes private tankers and ‘other sources’

Spatial variations The levels and patterns of use across sample wards grouped according to the condition of public supply and the proportion of slum households does not show a clear pattern. This may be due to the error in the group classification especially by income. The latter, as already mentioned, was based on the percentage of slum tenements in different wards and some general impressions about the nature of the neighbourhood.

However, as can be seen from Table 13, the mean per capita consumption is the lowest and the proportion of total consumption contributed by public systems is the highest in wards rated by officials as having ‘good’ public water supply. Wards with poor public supply also have a much lower degree of dependence on public supply but only a slightly higher level of average. It is interesting that the wards with moderate public supply report the higher level of mean consumption and also the lowest proportion obtained from public systems.

Table 12 : Consumption levels and contribution of public supply in sample wards classified by conditions of public supply Condition of Public supply

Number of wards number of wards with per capita consumption<50 lpcd

number of wards where the Public system accounts for >50% of total use

Good 13 9 9Medium 11 3 1Poor 7 4 2

Variations across income groupsA much clearer pattern emerges when we look at the levels, sources and uses of water by households classified by incomes as reported in the Survey. (Table 14) Per capita consumption clearly increases with income. The lowest income group consume around 50 lpcd, and this level increases progressively to around 80 lpcd in the 15+k group. This is largely a reflection of the fact that higher income groups consume more for washing, bathing and toilets. The lowest income group uses nearly a fifth of its total consumption for drinking and cooking, while the top group uses barely 9 percent. Among other uses, it is washing that seems to be the main reason for higher level and a larger share of total consumption as incomes increase.

Table 13: Per Capita Consumption based on Reported UseGroup Drinking Cocking Washing Bathing Toilet Other Total5K 4.6 (9%) 5.0 (10%) 18.0 (36%) 13.4 (26%) 8.1 (16%) 0.8 (2%) 49.95K-10K 4.2 (7%) 5.2 (9%) 22.7 (37%) 16.6 (27%) 11.6 (19%) 1.3 (2%) 61.610K-15K 3.4 (5%) 4.6 (6%) 33.5 (46%) 16.8 (23%) 13.4 (18%) 1.2 (2%) 72.915K-20K 2.9 (4%) 4.4 (5%) 39.7 (49%) 17.1 (21%) 13.2 (16%) 3.4 (4%) 80.7

The poorer households tend to depend more on metro water supply thru tankers and static tanks. This may be due to the study conducted at a time when the in-house supply was not there. The table shows that the poorer groups meet more than 50% of their daily requirement from public supply and the percentage of dependency decreases in higher income groups. The high-income groups depend more on own well (79%) sources. The dependency on bottled water is also more in high-income groups.

Table 14: Per capita consumption source wise*MW.Inside MW.Outside Ownwell Other’s well Bottled Total

5K 7.7 17.1 12.5 9.4 0.4 47.25K-10K 7.9 7.9 33.6 2.5 0.7 52.610K-15K 2.7 10.8 44.2 4.0 1.5 63.215K-20K 4.2 1.4 56.3 6.8 2.3 70.9*excludes private tankers.

Cost of waterTo get an idea on the amount spend by each hh to source water, sample house holds were asked on the annual tax paid to metro-water for water supply, amount spent to purchase water from tankers and bottled water.

The amount collected as tax per household by metro water is fixed as Rs.50 per month irrespective of the quantity consumed per household. Users do not pay anything for water from outside taps and hand pumps provided by Metro water. They are also supposed to get water from Metro sources outside the house through fixed tanks and mobile tankers free of charge. However in fact they pay for supply from these sources. The average expenditure is reported to be Rs.24.70 / Kilo-litre (KL) in the case of static tanks and Rs. 25.70/ KL from metro tankers.

Sample households spend about Rs12.10/KL on the average for water sourced from others wells. The average cost of bottled water is about Rs.1.30 per litre by purchasing bottled water.

In the case of water sourced from own wells the costs includes payment for energy used for lifting as wells as depreciation and maintenance, as well as interest on capital costs. We do not have sufficient information to estimate these costs. However, based on information regarding the average duration of operation of pumps, the number of wells, and assuming electricity charges at a notional Re 1 per unit, the energy costs alone would work out to Rs.0.70 per KL.

We did not collect information on the quantum and cost of water taken from private tankers. We assume that the average cost per tanker of 10,000 litres at Rs. 600. The average household size, based on the survey, is around 5.2 and the average per capita daily consumption is around 52 litres. The total consumption of an average household works out to 8112 litres per month. Based on the sourcewise composition of consumption and the rate per KL of different sources, the average expenditure per house works out to be Rs. 316 per month or Rs. 36 per KL. (Table 15)

Table 15: A rough estimate of cost incurred by an average household for its water Source Consumption

In lpcd Total Consumption in litres per household per month month

Cost in Rs.

Metro Inhouse 6.8 1061 50Metro outside 11.8 1840 46Own Well 26.5 4134 4Other well 6.3 983 12Bottled water 0.8 125 162private tankers 4.4 693 42

56.6 8836 316

Estimates of total domestic consumption in Chennai city

The estimates of mean per capita consumption (overall and by major sources) of sample households in different strata were applied to the estimated total number of households in each of them. (Table 16) Based on this, the total consumption of the city population from all sources during the period of the survey works out to 235 million litres per day (mlpd) and consumption from Metro Water sources to 80 million litres per day. Table 16: Estimated daily consumption by source, Chennai Corporation January 2004 (millon litres)

Source Consumption % share

Metro in house 27.8 11.8Metro outside house 52 22.1Own wells/ borewells 123.3 52.4Others’ wells 28.3 12.0

Bottled water 3.9 1.7

Total 235.3 100.00

At the time of the survey, Metro-water accounted for a little over a third of the total consumption. Surface sources being practically dry during this period, supply through the public system was entirely from groundwater extracted from wells bore wells and tube wells within the city limits and from wells outside. Though the survey was carried out at a time when there was no piped water supply, houses in some wards located in close proximity to the distribution lines got in-house supply to distribution mains. The greater part of public supply was provided through fixed public tanks, mobile public tankers and public hand pumps located outside consumers’ premises.

Sources other than Metro-water – which includes private wells and bore wells, private tankers and bottled water – accounted for about two thirds of the total domestic water consumption. The bulk of it was from private wells owned by users. But a sizeable amount (28 million litres) was taken from wells owned by others or from community wells.

Altogether 98 percent of the total consumption was contributed by groundwater. The balance is accounted by bottled water. Estimates of mean per capita consumption (overall and by uses) of the city’s population are presented in Table 17. Based on this, the total consumption of the city population for all uses during the period of the survey works out to 255 mld

Table 17: Estimated Daily water consumption for various uses Uses Quantity in Million litres

per dayDrinking 17.7Cooking 21.1Washing 100.1Bathing 65.7Toilet 45.3Other 5.1Total 255

It will be noticed that estimated total consumption by source is less than that based on reported quantities by uses. This difference is partly because the questions relating to source wise consumption did not elicit information on private tankers. It should also be noted that the estimate relates only to domestic use. They do not cover consumption by private and public institutions, commercial and industrial establishments. The total consumption including all users will obviously be higher than that of households.

The estimates are roughly corroborated by available data on the quantum of metro supply during the survey period (January 2004), which was marked by acute water scarcity. In this month Metro Water had introduced a system of supplying some 180 mlpd on alternate days (compared to some 300-400 mlpd daily in normal years) or an average of 90 mlpd every day which is higher than the survey based estimate of household consumption of 80 mlpd from metro water. The difference could be accounted by non-domestic consumption and wastage.

During the survey period the public system depended totally on groundwater extraction ie, water being tapped from the borewells present in the wells fields of AK basin (which is inclusive of both government borewells and the water purchased from the farmers whose borewells are in line with the supply main), southern coastal aquifer, and from the hand pumps fitted within the city limits. Which means that the total water consumption during scarcity periods includes public groundwater from outside, inside the city (the private groundwater wells and borewells in residences) and private water tankers that get water from the wells and borewells located on the fringes of Chennai city.

The Survey data gives information on the no of sample households with wells in each ward and in turn for all the nine groups was worked out. From this the total number of private wells in the city has been estimated as follows: (1) sample households in each of the 9 categories of wards have been grouped into single occupancy and multiple occupancy households; (2) on this basis, the total number of single and multiple occupancy households in the city have been estimated; (3) the number of wells in single occupancy residences is estimated by multiplying the total number of this class of households and the sample survey estimate of the number of open and bore wells per household in different strata; (4) in respect of multiple occupancy, we have assumed that on the average wells in this category serve 4 households. On this basis we estimate that there are about 4.2 lakh wells ( about 27,000 open wells and nearly 4 lakhs of borewells) in

Chennai city. The average no. of persons per household works out to 5.2 members per house hold. Considering an average per day extraction of about 400 litres per well per day then the daily extraction works out to about 168.9 MLD. Also the extraction calculated based on sources wise consumption (for wells and borewells) works out to about 170 MLD.

Characteristics of wells and their usage

Particulars of Own Well

The particulars of own wells ie., open dug wells and borewells present in the surveyed households were classified based on the reported income (Table –18). In general the no. of borewells is more than the open dugwells which is an indication of tapping water from the deeper source. Of the reported households 8% of them have open wells which are still in use and 54% depend on borewells. About 7.5% have both open well and borewell. The ratio of no. of well per house hold was calaculated for all the income group. The poor income group have one well for every 2 households (with more dependence on the public system) and the rest of the groups have almost a well in each household.

Table: 18No. of household reportingOW OW in Use BW OW+BW Total wells

5K 55 42 190 24 3115K-10K 30 37 279 34 38010K-15K 39 31 237 37 34415K-20K 8 5 71 13 97

132 115(8%) 777(54%) 108(7.5%)

Table : 19 Period of construction

No. of Open Well by Original DateNo. of Borewell by Original date

<1970 1970-80 1980-90 1990-2000 <1970 1970-80 1980-901990-2000

5K 15 17 25 14 5 1 1 1465K-10K 10 27 23 4 0 8 59 22910K-15K 7 34 23 13 2 7 67 19715K-20K 2 3 11 5 0 3 18 62

In general there is a gradual decline in the construction of open wells after 1980 in all the groups and the no. of borewell construction increases rapidly after 1980.

Table 20: Characteristics of wells based on Lifting Device, Type of Pump and Horse Power of Motor

No. by type of lifting deviceNo. by type of pump No. by type of HP

Manual Electric Centrifugal Jet 0.5HP 1HP 1.5HP 2HP5K 45 157 25 170 51 76 21 05K-10K 17 245 17 274 23 156 57 010K-15K 13 225 15 251 22 98 75 515K-20K 2 62 4 80 4 16 40 6

77 689 61 775

The wells were classified based on the type of lifting device (manual and electric). Manual extraction is an indication of shallow water table. Only 10% of the wells are used for manual extraction the rest of them are electric driven.

The wells were also classified based on the type of pump. The working head (water pulling capacity) of centrifugal pumps is only 30ft below ground level whereas the Jet pumps work up to 200ft. here again more than 90% of the wells are fitted with Jet pumps is an indication of tapping water from deep water table.

The classification of Motor based on HP also shows similar trend with more wells falling the 1hp and 1.5 hp motor which is normally used to pump water from depth between 100ft –150ft.

The Sample households were asked about the year of construction of the wells, their original and current depth. The information for open wells is presented in Table 21, 22 and those relating to bore wells in Table 23,24. While most could give information on year of construction and current depth, many either did not know or could not remember the original depth. About 360 sample house holds reported to have open wells of which 65% of them were not in use. More than three fourths of the wells were constructed before 90. the average depth of the open wells is about 30 feet below ground level. Most of the borewells were constructed after 1990 with their average depth around 90feet below ground level.

Table: 21 Year of Construction of Open wells with their mean Current and Original DepthYear of Construction Mean Depth

No. of wells No. reporting Original CurrentBefore 1970 35 10 27.4 28.370 – 80 83 48 34.1 33.380 – 90 88 47 29.9 27.1After 90 38 23 31.1 27.7Total 244

Table : 22 Year of Construction of Open wells with the frequency distribution of depthYear of construction

Frequency Dis. Of Open Wells by depth(ft)25 50 75 100

Before 1970 7 7 0 070 – 80 19 33 4 280 – 90 24 24 4 1After 90 13 9 2 2Total 63 73 10 5

Table : 23 Year of Construction of Bore wells with their mean Current and Original DepthYear of Construction No. of

BorewellsMean Depth

No. reporting Original CurrentBefore 1970 10 9 55.5 65.570 – 80 20 14 87.5 92.180 – 90 194 122 90.1 93.5After 90 664 422 92.7 94.1Total 888

Table : 24 Year of Construction of Open wells with the frequency distribution of depthYear of construction

Frequency Dis. Of Bore Wells by depth(ft)50 100 150 200 >250

Before 1970 3 1 0 0 070 – 80 2 7 3 2 180 – 90 26 83 9 6 11After 90 70 290 45 44 21Total 101 381 57 52 33

The house holds were asked to report on the frequency of pump operation in each day and the duration of hours. It was found that the average rate of pumping of wells to be 1.3 hrs daily

The households were asked to report on the time taken to fill up the over head tank / sump when the borewell/well is in operation and their storage capacity. Based on this the yield of the borewells in litres per minute(lpm) was worked out and the results are tabulated in the above table. About 40% of the wells fall within 16lpm ie., an yield of 1000 litres per hour, 36% of the households reported an yield of less than 2000 litres per hour and about 24% reported the borewell yield as more than 2000 litres per hour.

Rainwater harvesting

Due to over dependence on groundwater in the city there has been a progressive decline in the ground water levels reflected in the decrease of number of open wells in use and increase in the number of borewells. In order to conserve the groundwater within the city limits there has been a

considerable amount of initiatives taken by the state government in controlling the commercial exploitation of groundwater. The Chennai groundwater regulation act, which was passed in 1987, was mainly to curb the commercial groundwater exploitation within the city limit. This was followed by making rainwater harvesting (RWH) mandatory in multistory buildings. During 2001 RWH was made mandatory for all the new buildings and in 2003 it was made compulsory for all the buildings (existing and new) through an ordinance. But the general opinion about the implementation of this ordinance is that

the time frame given was too short the structures were not properly designed not many trained and skilled labours were available for implementation non availability of quality materials for implementation

Hence the households were asked to report on the design, implementation, cost and maintenance. About 92% of the surveyed households have reported RWH implemented out of which about 86% of the households implemented after the promulgaion of ordinance (ie., after august 2003) and about 5% before 2002.

With regards to the guidance sought to design the RWH system, nearly 11% got it designed with the help of Metro water, 12% of the sample households got it designed through consultants. Fairly large amount of of households (41%) sought the help of local plumbers in designing and about 24% self designed their own RWH system. 65% - 70% of the households have implemented rwh designed by plumber or self is an indication of

1. non availability of experts in designing nor the experts help was sort for designing2. quality of rwh structure (in general households in Chennai opted for the normal bore type

percolation pit which is cheaper but gets clogged and hence in-effective) Table: Percentage of sample house holds reporting on the help sought from different agencies for designing RWH system in their housesAgencies Approached by % of

house holds to get RWH design

Metro Water 11%NGO 0%Other Consultant 12%Plumber 41%Self 24%

Majority (66%) of te sample house holds got the system implemented through plumbers. About 9% engaged authorized contractors, 0.1 % on Voluntary NGO’s and about 11% depended others to implement.

Table : Percentage of sample house holds reporting on the help sought from different agencies to implement the RWH system in their houses

AgenciesApproached by % of house holds to get RWH design

NGO 0.1%Authorised Contractor 8.6%Plumber 66%Others 11%

With regard to the cost of RWH about 9% have spend less than Rs.1000, 31% have spend between Rs.1000 to Rs.2000 to get the structures installed. About 16% of the households reported spending between Rs.2000 – Rs. 3000 and an equal percentage reported spending more than Rs.3000 to get the structures implemented.Cost of RWH

Cost in Rs Percentage of Households

> 1000 9%1000 – 2000 31%2000 – 3000 16%> 3000 15.6%Non reported 28.4%

Majority of the households (more than 3/4th) reported tapping roof top water. Just 10% of the house holds have reported tapping surface run –off.

House holds reporting on the source of harvested water

Source Percentage of Households

Roof Water 79%Surface Water 2%Both 8%Non reported 11%

With respect to designs as shown in the table below about 52 % of the sample house holds have designed a proper system wherein the roof top water diverted to recharge well, percolation pit or stored in sumps. About 10% of the households have reported faulty structures. The rest have not reported on the design aspects.

Table: Design characteristics of RWHRWH Design Percentage of Sample

HouseholdsRoof top directed to existing OW/BW 38%Surface water directed to existing OW/BW 4%Roof top to recharge well 9%Surface water to recharge well 0.6%Roof top to percolation bore pit 14%Surface water to percolation bore pit 1.5%Roof top to percolation pit 24%Surface water to percolation pit 4%Rooftop to sump thro filter 5%Surface water to sump thro filter 0.8%

Of the total sample house holds 28% were aware of the maintenance required in RWH structures. Nearly 45% of the households were not aware of the maintenance aspects and 22% have not responded.