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 / 3
MEDIUM SUPPLY / 5 / 4 / 2
POOR 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 head
Total members / Education of house hold head
Adult / Children / Non literate / Elementary / Secondary / Diploma / Degree
6176 / 2022 / 110 / 216 / 410 / 86 / 688
Table – 3: Occupation of the sample house hold head
Occupation of house hold head
Self 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 / 245
5K – 10 K / 397 / 262 / 210
10K – 15 K / 333 / 215 / 277
>15 K / 97 / 83 / 72
All reporting households / 1427 / 58 / 118
Total 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 households

Public

Direct in-house

Outside tap/hp
Storage tank
Metro tanker /

834

417
450
178
Own well /

1000

Others well

/

50

Community well

/

5

Private tanker

/

45

Total

/

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 sources

Sources / Homes
Own Well and Metro tanker / 462
Own well and Other well / 23
Own well and Community well / 2
Own well and Private tanker / 31
Metro tanker and Other well / 116
Metro tanker and Community well / 73
Metro tanker and Private tanker / 18
Other well and Community well / 1
Own well, Metro tanker & Other well / 9
Own well, Metro & Private tanker / 6
Metro & 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 tanker / Other well / Comm. Well / Private tanker / Multiple sources / Total Homes
5k / 65 / 106 / 44 / 5 / 2 / 273 / 600
5k-10k / 101 / 45 / 5 / 0 / 3 / 39 / 397
10k-15k / 109 / 17 / 1 / 0 / 27 / 159 / 333
15k-20k / 51 / 0 / 0 / 0 / 12 / 25 / 97

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

Total households / No. of homes with OHT / No. of homes with Sump
5K / 600 / 171 / 40
5K-10K / 397 / 289 / 78
10K-15K / 333 / 300 / 142
15K-20K / 97 / 86 / 73
All / 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 use

Average 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 / All
Per capita No of hhs / 59 / 475 / 599 / 227 / 113 / 37 / 1510
Per Adult Unit No. of hhs / 34 / 366 / 539 / 327 / 172 / 72 / 1510

Distribution by use

The 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 : MeanPer capita consumption in litres per day for different uses*

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

Distribution by source of supply

Metrowater 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 13
Metro outside / 828 55 / 11.8 22
Own Well / 821 54 / 26.5 50
Other well / 351 23 / 6.3 l1.2
Bottled 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.