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. supply. Some years bac, a large scale survey of !hennai !orporation showed that the total v olume consumed per capita was considerably less than the norm of "#$ lpcd considered necessary in metropolitan areas and that public sources contributed co ntributed less than half of the total consumption. %hat groundwater e&tracted by privately owned wells and bore wells was the main private source and that groundwater levels in the city have been falling progressively was nown in a general way. 'ut no hard data were available. %he 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.
* %he survey is part of the !entre for Science and (nvironment)s ongoing wor on the current status, problems and prospects of water supply in urban areas of the country. ** (meritus +rofessor, Madras nstitute of -evelopment S tudies, !hennai *** ormer !entre for Science and (nvironment staff
Scope and Design of Survey
%he Survey, conducted during -ecember #$$/ and January #$$0, was limited to households within the limits of the !hennai !orporation. !ommercial and industrial establishments and other public and private institutions were not covered. A representative sample of "1"$ households was interviewed for collecting data. %he "11 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 2ater officials. 2ards within each of these categories were further categori3ed into upper, middle and lowincome neighbourhoods. %hough this was done in consultation with several nowledgeable persons, it is necessarily impressionistic. 2e thus had nine categories of wards. A stratified random sampling procedure was used to select a total of "1"$ households, the number that seemed feasible within the constraints of time and resources available. %he number of sample households to be selected in the 4 strata was allocated in proportion to the total number of households in each of them 5obtained from the "44" census6 Since the ward wise population of #$$" census was not available at the time of study7. t was further decided that households to be surveyed should be selected from a randomly selected sample of the streets within each sample ward and that at least randomly selected "$ households should be interviewed from each sample street. %he number of sample wards in each stratum and the number of sample streets in each sample ward was determined on this basis. %he sample wards and sample streets within each of them were chosen through random selection. A total of "1"$ sample households in "1" streets located in /" wards were covered by the survey. -etails are given in the annexure 1. %he location of the sample wards is shown in the accompanying map. %he survey schedule (see annexure ! was designed to elicit information of household characteristics, the sources on which they normally depended for different uses, and the actual 8uantity they obtained from different sources during the day prior to the interview, particulars of storage tans and sumps, purchase of water from metro taners and private taners, costs of getting water from different sources, the characteristics of wells9borewells 5including the time of their construction, deepening and current and original depth and power source7, and implementation of rainwater harvesting. %he interviews were conducted from late -ecember #$$/ through January #$$0 by postgraduate students in social wor from the Madras !hristian !ollege. %heir field wor was closely supervised and the filled in schedules scrutini3ed by +rof. Annadurai and -r.Mirium Samuel, head of that department and Sri J Saravanan. n 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 8uestions and give information. However some of the 8uestions and in some cases the instructions to field investigators were not framed clearly. or instance, the 8uestions relating to 8uantum of water used from different sources did not specify the contribution of private taners. %he treatment of multiple occupancy households and flats raised some difficulties in estimating overall consumption and use because the schedule did not include 8uestions on the number of households in such cases. nformation
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 8uestions. %hese problems notwithstanding, thans 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 e&ploitation 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. %hat the estimates of total consumption by sources and uses based on the survey data are broadly corroborated by estimates from other independent sources. (stimates of 8uantities consumed by purpose and source are based on informants) recollection of the number of pots and bucets used the day before the interview. %hese containers are generally, but not always, of two or three standard si3es. Moreover, the information obtained is based not on actual observation but on recollection of the respondents. %he data are therefore necessarily appro&imate. ;evertheless, a comparison of the estimates of total per capita consumption from the public system with the Metro 2ater figures of the 8uantity supplied during the survey period suggests that the survey estimates are in the right ball p ar. (stimates of per capita consumption for individual uses 5e&cept perhaps toilets7 also seem plausible. Characteristics of sample households
%he location of the /" sampled wards can be seen from map 1. %able" gives their distribution according to original stratification by conditions of public supply an d a notional assessment of relative prosperity based on the proportion of h ouseholds living in slums. %he location of the sample wards is shown in Map ". "a#le 1$ Distri#ution of sample %ards #y extent of pu#lic supply and average living conditions <++(= M--?( ?>2(= ;!>M( ;!>M( ;!>M( @>>- S<++? 1 1 / M(->= S<++? / # #
%he sample households had a total of B"CB members of whom roughly a third 5#$##7 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 selfemployed6 a little less than half as having regular employment. About an eighth of them are pensioners. %he proportion reporting casual wage employment is surprisingly small at B per cent.
"a#le & $ 'ducation and ccupation of the sample house hold head %otal members (ducation of house hold head Adult !hildren ;on literate (lementary Secondary -iploma -egree B"CB #$## ""$ #"B 0"$ DB BDD "a#le & )$ ccupation of the sample house hold head >ccupation of house hold head Self =egular (mployee =egular (mployee (mployed >rganised Sector
!asual 2age (mployment "#4
+ensioner "4"
>f the total surveyed house holds about 0#E fall in the income group of less than =s. 1$$$ per month, and about C percent more than =s."1$$$ per month. About B/ percent o f the sample households live in their own houses and the rest in rented accommodation. %he sample households are divided more or less e8ually between single occupancy homes and multiple occupancy houses. About "D percent of the households live in flats. %he relative importance of owned housing and single occupancy also varies with income. As may be e&pected, the proportion of households living in own houses and in single occupancy residences increases with income 5%able 07. "a#le $ Characteristics of +ouse holds %ith different income levels Household income ;o. of ?iving in own ?iving in single group in =s. households house occupancy F1G B$$ /$4 #01 1G "$ G /4C #B# #"$ "$G "1 G /// #"1 #CC I"1 G 4C D/ C# All reporting households "0#C 1D ""D %otal sample households "1"$ 4#C 4##
;ote some sample households did not provide the information. their number under each characteristic is indicated as nonreporting -ependence on sources %he sources of supply as reported by the sample households, and the number of households reporting different sources are presented in table 1. =oughly 11 percent of the sample households have direct metro water connections6 B0 percent report accessing fi&ed tans, taps and hand pumps provided by Metro 2ater6 and about "" percent metro taners. ;early two thirds of sample households have their own wells or bore wells. Access through others) wells and private taners is reported by less than 1 percent each of the total households. %he fact that the number of sources is nearly double the number of households shows that !hennaities depend on multiple sources for their water supply.
"a#le & ,$ -um#er of households reporting different means of access to %ater supply Sources Sample households +ublic -irect inhouse D/0 >utside tap9hp 0"C Storage tan 01$ Metro taner "CD >wn well "$$$ >thers well 1$ !ommunity well 1 +rivate taner 01 %otal ./.
%his is further highlighted by table B, which gives the situation at the time of the survey in respect of sources from which households draw their supplies. >nly 0$ percent of sample households report using a single source mostly wells 50$C households7, followed by metro taners 5"CD7 and private taners 5017. >f those who report multiple sources, by far the largest number supplement own well with other sources6 a si3eable number use metro water taners along with other sources 5again mostly wells7 %he large maKority of households depend on a single source for each purpose, but different sources for different purposes. A si3eable proportion 5ranging from one eighths in the case of toilets to one fifth for drining7 uses two sources. A much smaller number of respondents use the three sources. >nly 0$ percent of sample households report using a single source mostly wells 50$C households7, followed by metro taners 5"CD7 and private taners 5017. >f those who report multiple sources, by far the largest number supplement own well with other sources6 a si3eable number use metro water taners along with other sources 5again mostly wells7 5%able B7 "a#le 0$ Dependence of sample households on multiple sources Sources >wn 2ell and Metro taner >wn well and >ther well >wn well and !ommunity well >wn well and +rivate taner Metro taner and >ther well Metro taner and !ommunity well Metro taner and +rivate taner >ther well and !ommunity well >wn well, Metro taner L >ther well >wn well, Metro L +rivate taner Metro L +rivate taner, >ther well
Homes 0B# #/ # /" ""B C/ "D " 4 B "
%he pattern of source dependence varies with income. %aing all uses together, 5see %able D7 the proportion of sample households reporting dependence on wells as the sole source increases progressively from about "" percent in the lowest to more than half in the highest income group6 dependence on metro taners is inversely related to income the proportion being roughly a si&th of lowest income group and practically 3ero in the "1G group6 on the other hand, dependence on private taners as the sole source is negligible in low income groups and is relatively high 5"# percent7 in the highest. %he incidence of multiple sources does not show a clear pattern. "a#le /$ -o of sample households #y income group reporting use from various sources >wn well Met >ther !omm. +rivate Multiple %otal taner well 2ell taner sources Homes 1 B1 "$B 00 1 # #C/ B$$ 1"$ "$" 01 1 $ / /4 /4C "$"1 "$4 "C " $ #C "14 /// "1#$ 1" $ $ $ "# #1 4C "$1 households in the 1 group, #$0 households in the 1"$ group, #$households in the "$ "1 group and 1households in the I"1 group haven)t responded
%his is further highlighted by table D, which gives the number of households reporting use of different sources for different purposes. %he following features are noteworthy +ublic supply from tap inside and outside the house is used for practically all purposes more or less with e8ual fre8uency. - i&ed tans and taners of the public system are used for drining and cooing far more fre8uently than for other uses - 2ells 5own or others)7 are used mainly for washing, bathing and toilets. - +rivate taner supply is used by si3eable number of households in all uses, but more so for purposes other than drining. - t is noteworthy that nearly a fourth of the households use bottled water for drining and about D percent for cooing. "a#le 2$ -um#er of sample households using different source for different uses ther Households +ublic in house #C$ #C" #$0 #$4 "DC #D ""B4 +ublic outside 04 00 1$ 1$ 0D #B #BC +ublic handpump9tap "0/ "04 "1$ "## ""D #4 C"" +ublic fi&ed tan "CB "B$ 14 B# 1# B$ 1B4 +ublic taner 11D 104 ##D #"B "BB #D "C01 >wn well "1/ /#1 D$0 D$D D"" "0C /$0D >thers well "C /" B$ B/ B$ #D #14 !ommunity well9handpump 1 4 DB D1 D1 "0 #D0 +rivate taner 0" 4" 4C ""$ DD /C 0B0 'ottled water 0#0 ""0 " $ $ $ 1/4 %otal households "D/B "C0/ "C/4 "C#1 "B"1 /4C 4$11
-
%he survey data further show that households with less than =s 1$$$ per month depend on public supply both inhouse and outside for all the daily uses. 2ater from public taners and from fi&ed tans is used mainly for drining and cooing purposes. 2ater from private wells is used mainly for washing and bathing purposes. %he depe ndence of bottled water is very low in this group. %his pattern is noticed in the middle groups as well e&cept that a larger proportion of them depend on bottled water for drining. %hose in the highest income group depend on public system to a much smaller e&tent than others. %his group depends more on own wells and private taners for all uses e&cept for drining. %he dependence on bottled water is 8uite high for drining and cooing in this group. Storage devices
!hennai households combine use of multiple sources with the use of overhead tans and sumps to store water. ;early 11 percent of sample households report having overhead tans 5with capacities ranging from less than 1$$ litres to over D$$$ litres7 and somewhat over a fifth have sumps !apacities ranging between less than "$$$ litres to over "$,$$$ litres7. %he proportion of households reporting >H%s and Sumps is relatively higher among single occupancy households. %he incidence of these storage facilities is relatively limited in the case of households in the lowest income group 5where about #D percent of households report >H% and barely C percent sumps7 while it is practically universal in the highest income group 5DD percent with >H%s and C1 percent with Sumps7 "a#le .$ Distri#ution of +"s and Sumps #y income groups %otal ;o. of homes ;o. of homes households with >H% with Sump 1G B$$ "C" 0$ 1G"$G /4C #D4 CD "$G"1G /// /$$ "0# "1G#$G 4C DB C/ All "0#C D0B /// About D/ households of the total sample of "1"$ h aven)t reported on the monthly income 3atterns of %ater consumption 3er capita use Average per capita daily domestic water consumption of sample households during the survey period 5in -ecember $/January $07 ranged from less than #1 litres to more than "#1 litres. About one third of the households reported consumption rate between #1 and 1$ lpcd and around /4 percent between1$ and C1 lpcd. %he range of variation is considerably reduced if we adKust for differences in the composition of households in terms of the proportion of adults and children, Assuming that two children are e8uivalent to one adult un it,
"a#le & 14$ Fre5uency distri#ution of sample house holds #y level of per capita daily use ?evel of daily use in litres per day
+er capita of hhs +er Adult
F#1
#11$
1$C1
C1"$$
"$$"#1
I"#1
All
14
0C1
144
##C
""/
/C
"1"$
/0
/BB
1/4
/#C
"C#
C#
"1"$
;o ;o.
Distribution by use %he maKor part 5nearly two thirds7 is used for cooing and washing6 and a little over a si&th for toilets. %he average use for drining is 0 lpcd an d for cooing 0.4 lpcd. +er capita usage both overall and for different purposes varies the coefficient of variation which is a measure of the degree of variation is around /$ percent for total usage6 the variation is much higher than average in the usage for washing and toilet6 about the same as average for drining and the least for bathing.
"a#le 11 $ 6ean 3er capita consumption in litres per day for different uses* -rining !ooing 2ashing 'athing %oilet >thers %otal Mean 0.$ 0.4 ##.B "1." "$./ "." 1D." Standard -eviation ".# "." "#.# #.4 0.$ ".D "C./ cv $./$ $.#/ $.10 $."4 $./4 ".11 $./$
Distribution by source of supply Metrowater accounts for about /1 percent of the reported consumption of sample households, the maKor part of it from tans, pumps and taps outside the side the house as well as metro taners. %he maKor part is from wells about half the total use is accounted by own wells and the balance by others)wells.5%able "#7
"a#le & 1 $ Source %ise per capita consumption of sample households* Source Households reporting !onsumption number and E of lpcd E of total sample household consumers Metro nhouse /#" #" B.D "/ Metro outside D#D 11 "".D ## >wn 2ell D#" 10 #B.1 1$ >ther well /1" #/ B./ l".# 'ottled water /D4 #1 $.D ".1 *(&cludes private taners and :other sources) Spatial variations %he 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. %his may be due to the error in the group classification especially by income. %he 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 %able "/, 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. 2ards with poor public supply also have a much lower degree of dependence on public supply but only a slightly higher level of average. t 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. "a#le 1 $ Consumption levels and contri#ution of pu#lic supply in sample %ards classified #y conditions of pu#lic supply !ondition of +ublic ;umber of wards number of wards with number of wards supply per capita where the +ublic consumption system accounts for F1$ lpcd I1$E of total use @ood "/ 4 4 Medium "" / " +oor C 0 #
Variations across income groups A much clearer pattern emerges when we loo at the levels, sources an d uses of water by households classified by incomes as reported in the Survey. 5%able "07 +er capita consumption clearly increases with income. %he lowest income group consume around 1$ lpcd, and this level increases progressively to around D$ lpcd in the "1 group. %his is largely a reflection of the fact that higher income groups consume more for washing, bathing and toilets. %he lowest income group uses nearly a fifth of its total consumption for drining and cooing, while the top group uses barely 4 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.
%able "/ +er !apita !onsumption based on =eported
%oilet D." 5"BE7 "".B 5"4E7 "/.0 5"DE7 "/.# 5"BE7
>ther $.D 5#E7 "./ 5#E7 ".# 5#E7 /.0 50E7
%otal 04.4 B".B C#.4 D$.C
%he poorer households tend to depend more on metro water supply thru taners and static tans. %his may be due to the study conducted at a time when the inhouse supply was not there. %he table shows that the poorer groups meet more than 1$E of their daily re8uirement from public supply and the percentage of dependency decreases in higher income groups. %he highincome groups depend more on own well 5C4E7 sources. %he dependency on bottled water is also more in highincome groups. "a#le 1$ 3er capita consumption source %ise* M2.nside M2.>utside >wnwell >ther)s well 'ottled
%otal
1G C.C "C." 1G"$G C.4 C.4 "$G"1G #.C "$.D "1G#$G 0.# ".0 *e&cludes private taners.
"#.1 //.B 00.# 1B./
4.0 #.1 0.$ B.D
$.0 $.C ".1 #./
0C.# 1#.B B/.# C$.4
Cost of %ater %o get an idea on the amount spend by each hh to source water, sample house holds were ased on the annual ta& paid to metrowater for water supply, amount spent to purchase water from taners and bottled water.
%he amount collected as ta& per household by metro water is fi&ed as =s.1$ per month irrespective of the 8uantity consumed per household. wn 2ell #B.1 0"/0 0 >ther well B./ 4D/ "# 'ottled water $.D "#1 "B# private taners 0.0 B4/ 0# 1B.B DD/B /"B
'stimates of total domestic consumption in Chennai city
%he estimates of mean per capita consumption 5overall and by maKor sources7 of sample households in different strata were applied to the estimated total number of households in each of them. 5%able "B7 'ased on this, the total consumption of the city population from all sources during the period of the survey wors out to #/1 million litres per day 5mlpd7 and consumption from Metro 2ater sources to D$ million litres per day. "a#le 10$ 'stimated daily consumption #y source7 Chennai Corporation 8anuary 44 (millon litres!
Source Metro in house Metro outside house >wn wells9 borewells
!onsumption
E share
#C.D
"".D
1#
##."
"#/./
1#.0
>thers) wells
#D./
"#.$
'ottled water
/.4
".C
%otal
#/1./
"$$.$$
At the time of the survey, Metrowater accounted for a little over a third of the total consumption. Surface sources being practically dry during this period, supply through the public system was entirely from groundwater e&tracted from wells bore wells and tube wells within the city limits and from wells outside. %hough the survey was carried out at a time when there was no piped water supply, houses in some wards located in close pro&imity to the distribution lines got inhouse supply to distribution mains. %he greater part of public supply was provided through fi&ed public tans, mobile public taners and public hand pumps located outside consumers) premises. Sources other than Metrowater which includes private wells and bore wells, private taners and bottled water accounted for about two thirds of the total domestic water consumption. %he bul of it was from private wells owned by users. 'ut a si3eable amount 5#D million litres7 was taen from wells owned by others or from community wells. Altogether 4D percent of the total consumption was contributed by groundwater. %he balance is accounted by bottled water. (stimates of mean per capita consumption 5overall and by uses7 of the city)s population are presented in %able "C. 'ased on this, the total consumption of the city population for all uses during the period of the survey wors out to #11 mld
"a#le 1/$ 'stimated Daily %ater consumption for various uses
ther %otal
Nuantity in Million litres per day "C.C #"." "$$." B1.C 01./ 1." #11
t will be noticed that estimated total consumption by source is less than that based on reported 8uantities by uses. %his difference is partly because the 8uestions relating to source wise consumption did not elicit information on private taners. t should also be noted that the estimate relates only to domestic use. %hey do not cover consumption by private and public institutions, commercial and industrial establishments. %he total co nsumption including all users will obviously be higher than that of households. %he estimates are roughly corroborated by available data on the 8uantum of metro supply during the survey period 5January #$$07, which was mared by acute water scarcity. n this month Metro 2ater had introduced a system of supplying some "D$ mlpd on alternate days 5compared to some /$$0$$ mlpd daily in normal years7 or an average of 4$ mlpd every day which is higher than the survey based estimate of household consumption of D$ mlpd from metro water. %he difference could be accounted by nondomestic consumption and wastage. -uring the survey period the public system depended totally on groundwater e&traction ie, water being tapped from the borewells present in the wells fields of AG basin 5which is inclusive of both government borewells and the water purchased from the farmers whose borewells are in line with the supply main7, southern coastal a8uifer, and from the hand pumps fitted within the city limits. 2hich means that the total water consumption during scarcity periods includes public groundwater from outside, inside the city 5the private groundwater wells and borewells in residences7 and private water taners that get water from the wells and borewells located on the fringes of !hennai city. %he Survey data gives information on the no of sample households with wells in each ward and in turn for all the nine groups was wored out. rom this the total number of private wells in the city has been estimated as follows 5"7 sample households in each of the 4 categories of wards have been grouped into single occupancy and multiple occupancy households6 5#7 on this basis, the total number of single and multiple occupancy households in the city have been estimated6 5/7 the number of wells in single occupancy residences is estimated by multiplying the total number of this class of households and the sample survey estimate of the number of open and bore wells per household in different strata6 507 in respect of multiple occupancy, we have assumed that on the average wells in this category serve 0 households. >n this basis we estimate that there are about 0.# lah wells 5 about #C,$$$ open wells and nearly 0 lahs of borewells7 in
!hennai city. %he average no. of persons per household wors out to 1.# members per house hold. !onsidering an average per day e&traction of about 0$$ litres per well per day then the daily e&traction wors out to about "BD.4 M?-. Also the e&traction calculated based on sources wise consumption 5for wells and borewells7 wors out to about " C$ M?-. Characteristics of %ells and their usage 3articulars of %n Well
%he particulars of own wells ie., open dug wells and borewells present in the surveyed households were classified based on the reported income 5%able "D7. n general the no. of borewells is more than the open dugwells which is an indication of tapping water from the deeper source. >f the reported households DE of them have open wells which are still in use and 10E depend on borewells. About C.1E have both open well and borewell. %he ratio of no. of well per house hold was calaculated for all the income group. %he poor income group have one well for every # households 5with more dependence on the public system7 and the rest of the groups have almost a well in each household. "a#le$ 12 ;o. of household reporting >2 >2 in
'2 "4$ #C4 #/C C" CCC510E7
>2'2 %otal wells #0 /"" /0 /D$ /C /00 "/ 4C "$D5C.1E7
"a#le $ 1. 3eriod of construction
;o. of >pen 2ell by >riginal -ate
;o. of 'orewell by >riginal date
"44$ F"4C$ "4C$D$ "4D$4$ "44$#$$$ F"4C$ "4C$D$ "4D$4$ #$$$ 1G "1 "C #1 "0 1 " " "0B 1G"$G "$ #C #/ 0 $ D 14 ##4 "$G"1G C /0 #/ "/ # C BC "4C "1G#$G # / "" 1 $ / "D B# n general there is a gradual decline in the construction of open wells after "4D$ in all the groups and the no. of borewell construction increases rapidly after "4D$.
"a#le 4$ Characteristics of %ells #ased on 9ifting Device7 "ype of 3ump and +orse 3o%er of 6otor ;o. by type of ;o. by type of lifting device pump ;o. by type of H+ Manual (lectric !entrifugal Jet $.1H+ "H+ 1G 01 "1C #1 "C$ 1" CB 1G"$G "C #01 "C #C0 #/ "1B "$G"1G "/ ##1 "1 #1" ## 4D "1G#$G # B# 0 D$ 0 "B CC BD4 B" CC1
".1H+ #" 1C C1 0$
#H+ $ $ 1 B
%he wells were classified based on the type of lifting device 5manual and electric7. Manual e&traction is an indication of shallow water table. >n ly "$E of the wells are used for manual e&traction the rest of them are electric driven. %he wells were also classified based on the type of pump. %he woring head 5water pulling capacity7 of centrifugal pumps is only /$ft below ground level whereas the Jet pumps wor up to #$$ft. here again more than 4$E of the wells are fitted with Jet pumps is an indication of tapping water from deep water table. %he classification of Motor based on H+ also shows similar trend with more wells falling the "hp and ".1 hp motor which is normally used to pump water from depth between "$$ft "1$ft. %he Sample households were ased about the year of construction of the wells, their original and current depth. %he information for open wells is presented in %able #"7 ## and those relating to bore wells in %able #/,#0. 2hile most could give information on year of construction and current depth, many either did not now or could not remember the original depth. About /B$ sample house holds reported to have open wells of which B1E of them were not in use. More than three fourths of the wells were constructed before 4$. the average depth of the open wells is about /$ feet below ground level. Most of the borewells were constructed after "44$ with their average depth around 4$feet below ground level. "a#le$ 1 :ear of Construction of pen %ells %ith their mean Current and riginal Depth ear of !onstruction Mean -epth ;o. of wells ;o. reporting >riginal !urrent 'efore "4C$ /1 "$ #C.0 #D./ C$ D$ D/ 0D /0." //./ D$ 4$ DD 0C #4.4 #C." After 4$ /D #/ /"." #C.C %otal #00
"a#le $ :ear of Construction of pen %ells %ith the fre5uency distri#ution of depth ear of re8uency -is. >f >pen 2ells by construction depth5ft7 , ,4 /, 144 'efore "4C$ C C $ $ C$ D$ "4 // 0 # D$ 4$ #0 #0 0 " After 4$ "/ 4 # # %otal B/ C/ "$ 1
"a#le $ ) :ear of Construction of ;ore %ells %ith their mean Current and riginal Depth ear of !onstruction ;o. of Mean -epth 'orewells ;o. reporting >riginal !urrent 'efore "4C$ "$ 4 11.1 B1.1 C$ D$ #$ "0 DC.1 4#." D$ 4$ "40 "## 4$." 4/.1 After 4$ BB0 0## 4#.C 40." %otal DDD "a#le $ :ear of Construction of pen %ells %ith the fre5uency distri#ution of depth ear of re8uency -is. >f 'ore 2ells by construction depth5ft7 ,4 144 1,4 44 <,4 'efore "4C$ / " $ $ $ C$ D$ # C / # " D$ 4$ #B D/ 4 B "" After 4$ C$ #4$ 01 00 #" %otal "$" /D" 1C 1# //
%he house holds were ased to report on the fre8uency of pump operation in each day and the duration of hours. t was found that the average rate of pumping of wells to be "./ hrs daily %he households were ased to report on the time taen to fill up the over head tan 9 sump when the borewell9well is in operation and their storage capacity. 'ased on this the yield of the borewells in litres per minute5lpm7 was wored out and the results are tabulated in the above table. About 0$E of the wells fall within "Blpm ie., an yield of "$$$ litres per hour, /BE of the households reported an yield of less than #$$$ litres per hour and about #0E reported the borewell yield as more than #$$$ litres per hour. =ain%ater harvesting
-ue 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. n order to conserve the groundwater within the city limits there has been a
considerable amount of initiatives taen by the state government in controlling the commercial e&ploitation of groundwater. %he !hennai groundwater regulation act, which was passed in " 4DC, was mainly to curb the commercial groundwater e&ploitation within the city limit. %his was followed by maing rainwater harvesting 5=2H7 mandatory in multistory buildings. -uring #$$" =2H was made mandatory for all the new buildings and in #$$/ it was made compulsory for all the buildings 5e&isting and new7 through an ordinance. 'ut 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 silled labours were available for implementation • non availability of 8uality materials for implementation • Hence the households were ased to report on the design, implementation, cost and maintenance. About 4#E of the surveyed households have reported =2H implemented out of which about DBE of the households implemented after the promulgaion of ordinance 5ie., after august #$$/7 and about 1E before #$$#. 2ith regards to the guidance sought to design the =2H system, nearly ""E got it designed with the help of Metro water, "#E of the sample households g ot it designed through consultants. airly large amount of of households 50"E7 sought the help of local plumbers in designing and about #0E self designed their own =2H system. B1E C$E of the households have implemented rwh designed by plumber or self is an indication of ". non availability of e&perts in designing nor the e&perts help was sort for designing #. 8uality of rwh structure 5in general households in !hennai opted for the normal bore type percolation pit which is cheaper but gets clogged and hence ineffective7 "a#le$ 3ercentage of sample house holds reporting on the help sought from different agencies for designing =W+ system in their houses Agencies Approached by E of house holds to get =2H design Metro 2ater ""E ;@> $E >ther !onsultant "#E +lumber 0"E Self #0E
MaKority 5BBE7 of te sample house holds got the system implemented through plumbers. About 4E engaged authori3ed contractors, $." E on Voluntary ;@>)s and about ""E depended others to implement.
"a#le $ 3ercentage of sample house holds reporting on the help sought from different agencies to implement the =W+ system in their houses Approached by E of Agencies house holds to get =2H design ;@> $."E Authorised !ontractor D.BE +lumber BBE >thers ""E
2ith regard to the cost of =2H about 4E have spend less than =s."$$$, /"E have spend between =s."$$$ to =s.#$$$ to get the structures installed. About "BE of the households reported spending between =s.#$$$ =s. /$$$ and an e8ual percentage reported spending more than =s./$$$ to get the structures implemented. !ost of =2H !ost in =s I "$$$ "$$$ #$$$ #$$$ /$$$ I /$$$ ;on reported
+ercentage of Households 4E /"E "BE "1.BE #D.0E
MaKority of the households 5more than /90th7 reported tapping roof top water. Just "$E of the house holds have reported tapping surface run off. House holds reporting on the source of harvested water Source =oof 2ater Surface 2ater 'oth ;on reported
+ercentage of Households C4E #E DE ""E
2ith respect to designs as shown in the table below about 1# E of the sample house holds have designed a proper system wherein the roof top water diverted to recharge well, percolation pit or stored in sumps. About "$E of the households have reported faulty structures. %he rest have no t reported on the design aspects.
"a#le$ Design characteristics of =W+ =2H -esign
=oof top directed to e&isting >29'2 Surface water directed to e&isting >29'2 =oof top to recharge well Surface water to recharge well =oof top to percolation bore pit Surface water to percolation bore pit =oof top to percolation pit Surface water to percolation pit =ooftop to sump thro filter Surface water to sump thro filter
+ercentage of Sample Households /DE 0E 4E $.BE "0E ".1E #0E 0E 1E $.DE
>f the total sample house holds #DE were aware of the maintenance re8uired in =2H structures. ;early 01E of the households were not aware of the maintenance aspects and ##E have not responded.
