Determinants of water quality, availability and use in Kurunegala, Sri Lanka

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1 i DE ABSTRACT Y/ffl P. OTHER Dtrminants of watr quality, availability and us in Kurungala, Sri Lanka 7". E. Mrtns, M.A. Frnando, T. F. dc. Marshall, B. R. Kirkwood, S. Cairncross.A- Radalowicz Dpartmnt of Epidmiology and Population Scincs, London School of Hygin and Tropical Mdicin, London, U.K. ' Dpartmnt of Community Mdicin, Faculty of Mdicin, Univrsity or Pradniya, Pradniya, Sri Lanka 89 Abstract Btwn January 1987 and Fbruary 1988, 4590 homs of childrn undr fiv yars of ag wr visitd in thr aras of Kurungala district, Sri Lanka and data wr collctd on watr rlatd practics. 60% of th population usd protctd wlls, 30% usd unprotctd sourcs and 10% usd handpumps on borhols or pipd supplis. 90% of housholds had a sourc lss than 1 km away. Man watr consumption was abov 25 litrs pr capita pr day and did not corrlat with th distanc to sourc. Sampls of drinking watr wr collctd and facal coliform lvls wr dtrmind in sampls of stord watr from 3092 housholds and in sampls from th watr sourcs usd by 1043 of ths housholds. Th absnc or prsnc of organisms in ach sampl, and th gomtric man count in sampls with organisms wr usd as indics of contamination. Both indics changd with sason and varid btwn aras and btwn typs of watr sourc. Th proportion of positiv sourc sampls was uniformly high with th xcption of pipd supplis and handpumps. Th man count was highst for unprotctd sourcs. Thr was no vidnc that ground watr contamination occurrd in borhols. With stord sampls, boiling appard to rduc contamination markdly. Th proportion of positiv stord watr sampls was also lowr with th us of diffrnt vssls for collction and storag, with storag insid th hous, and with us of a storag containr othr than an arthnwar pot. Bcaus surfac watr pollution appars to b important it is proposd that hadwalls and drainag aprons b built around unprotctd sourcs. Facal contamination at th sourc may hav mor public halth significanc than contamination of stord watr. In this rspct public hygin may play an important rol in rducing watr pollution at handpumps or protctd wlls. Introduction Factors that dtrmin th pollution of watr or its availability in rural aras of th dvloping world ar of major intrst to plannrs of watr supplis. In th last two dcads it has bcom incrasingly apparnt that, far from bing uniform, th conditions ncssary for th succssful im- Trop.Md. Parasit.41 (1990)89-97 GorgThimVrlagSluttgart Nw York pr-rerekce CENTKf\ PLY AMU (W?CJ. plmntation of watr supply programms vary with gographical and sociocultural diffrncs (Schnidr t al., 1978). Many of thos who work to improv rural watr supplis in dvloping countris hav broadnd thir intrst from th tchnical and conomic fild to adopt a mor comprhnsiv approach taking fullr account of th watr usr's physical and cultural nvironmnt. Watr is closly bound up with th livs and halth of popl. It is thus a complx task to prdict th bnfits that might b xpctd from th improvmnt of watr sourcs which, in dvloping countris, ar oftn scarc or unsuitabl. Improvd watr supplis can bnfit a rural population in a varity of ways. Halth bnfits in particular can rsult indirctly from tim savings ( Caimcross and Cliff, 1987) as wll as dirctly from changs in hygin practics, and th consumption of watr fr from pathogns and contaminants. In rural Sri Lanka, as in many parts of th world, drinking watr and watr usd for domstic purposs is carrid hom from th sourc and is stord in vssls until consumption. Drinking watr quality can thrfor b affctd by contamination at th sourc, during th collction procss and also during storag (Rajaskaran t al., 1977; Fachm t al., 1978). Thr may b dramatic changs in th contnt of pathogns during this procss, for xampl if th watr is boild. This papr prsnts th rsults of an invstigation of watr quality, watr consumption and watr sourc choic which formd part of a largr study of padiatric diarrhoal disas in Kurungala, Sri Lanka. Matrials and mthods Study population Th study ara had a population of approximatly 360,000 inhabitants and has bn dscribd lswhr (Mrtns t al., 1990a). Th sampls of drinking watr wr collctd at th housholds of th childrn agd lss than fiv yars who had bn rcruitd in a cas-control study of diarrhoa and in cross-sctional survys. Thr distinct groups of childrn wr includd; childrn rporting to clinics with diarrhoa (cass), childrn rporting to clincis with complaints unrlatd to watr supply and sanitation (clinic controls) and childrn slctd at random from th community (community controls). Dtails of th slction of childrn ar givn in th third papr of thissris (Mrtns tal., 1990b). For childrn rcruitd at clinics th sampl of drinking watr was, on avrag, collctd on wk aftr th child's disas. Th subsampl of cass and clinic-basd controls whos homs wr to

2 90 Trop. Md. Parasit. 41 Mrtns, T.E..M.A. Frnando, T. F.dC. Marshalltal. b visitd wr slctd at random vry wk and an avrag of 40 visits wr prformd pr wk btwn January 1987 and Fbruary A watr sampling visit was carrid out for th community controls at th tim of cross-sctional survys in th sam catchmnt aras covrd by th rcruiting hospitals. Sinc facal contamination of drinking watr quality may chang during th collction and storag procss (Rajaskaran t al., 1977; Fachm t al., 1978), sampls wr collctd not only from public and privat sourcs but also from houshold watr storag vssls. At th hous th watr stord for drinking was sampld and in vry third houshold watr was also sampld dirctly from th sourc. Houshold intrviws and obsrvations Two sparat hom visits wr conductd for th childrn rcruitd at hospitals. On for th collction of watr spcimns and assssmnt of th watr quality and on whr information on watr sourc choic and watr consumption was collctd (Mrtns t al., 1990a). In th community, on singl visit was mad at hom in thr diffrnt aras. Mothrs wr intrviwd about thir choic of drinking watr sourc and whthr a diffrnt sourc was usd for othr houshold purposs. Th houshold was also askd to stimat th tim rquird for a rturn journy to ach sourc, and th rsult chckd by walking th distanc. An stimat of th houshold's ovrall watr consumption was mad by asking how many watr collction journys wr mad on an avrag day, and by stimating volum of th vssl normally usd. Th rsult was xprssd in litrs pr capita pr day (I. c.d.). Additional qustions wr askd rlating to hygin practics and socio-conomic factors. Environmntal microbiology All sampls wr collctd in strilisd glass and plastic bottls using standard procdurs (Chsbrough, 1984; WHO, 1984). In ordr to assss th quality of th watr that popl usually drink, no strilisation of th mouth of a tubwll or of th collcting buckt for shal low wlls or th storag vssl was carrid out. In addition, 60 sampls of tubwll watr wr takn aftr strilising th mouth of th pump in ordr to assss th quality of th ground watr. Bottls wr transportd in coolboxs dsignd to maintain th tmpratur btwn 4 C and 8 C. Sampls rachd th laboratory within 3-6 hours of collction. Th laboratory tchnician was not awar of th idntity or disas status of th child or th typ of watr sourc whn prforming th microbiological analyss. Quality control Quality control chcks wr prformd rgularly using two diffrnt procdurs. First, distilld stril watr in bottls lablld in such a way that thy could not b rcognizd from othr usual sampls, wr tstd for bactriological contamination twic a wk. No colonis appard on any of ths tst sampls. Scond, bottls containing watr from th sam sourc or vssl wr lablld with diffrnt numbrs and handd ovr to th laboratory. Counts wr thn compard and avagd whn clos agrmnt was rachd on th counts. In ight out of 91 such sampls th two counts wr in complt disagrmnt, and th ovrall rsult was xcludd from th analyss. Thirdly, th sam sampl wasfiltrdtwic and colonis wr countd sparatly by two prsons. Thr was 97% agrmnt btwn th counts. Statistical mthods Spcimns wr classifid by th prsnc or absnc of facal coliforms (FC). Among th sampls with coliforms, th mans of th logarithms (bas 10) of th counts wr usd to giv gomtric man counts. Th ffct of truncation of th high counts was assssd by comparing th mans calculatd with cnsord valus qual to 2000 or 10,000, and th mans adjustd for cnsoring by Wolyntz's mthod (1979). Th proportions with facal coliforms and th man counts wr thn classifid by th factors of intrst, such as sourc, sason, and boiling. To xplor th combind ffcts of svral factors on watr quality, rgrssion mthods wr usd. First, th proportion of positiv spcimns was usd as dpndnt variabl in logistic rgrssion modls. Scond, th log count among positiv spcimns was usd as dpndnt variabl in ordinary last squars rgrssion. Statmnts of statistical significanc ar basd on chi-squar and t- tsts and on th rsults of fitting th rgrssion modls. In th logistic rgrssions, whr a gratr variability than xpctd from th binomial distribution occurrd, th tst statistics wr adjustd by th disprsion paramtr, stimatd from th Parson chi-squar (McCullagh and Nldr, 1983). Mmbran filtration was carrid out for all sampls using two fild tsting kits and svral incubators. All sampls wr kpt at 4 C. on arrival in th laboratory and wr filtrd and 2.5 ml of strilisd lactos cultur mdium (mmbran lauryl sulphat broth, MLSB) wr addd undr asptic conditions. Th innoculatd cultur dishs wr thn incubatd at 44.5 C for 18 hours and xamind for th prsnc of facal coliforms (FC) (WHO, 1984). Th numbr of yllow colonis prsnt on th dish aftr incubation was thn rcordd (Chsbrough, 1984). Th choic of ithr a filtration volum of 5 or 25 ml dpndd on th xpctd lvl of contamination, which varid with sasonal rainfall lvls. At low lvls of contamination, good prcision in conform counts can b obtaind from ithr tst volum but th snsitivity of th 5 ml volum is poor. Howvr, with high lvls of contamination th 25 ml volum givs poorr prcision. Thrfor, in th priod of lowr contamination (Jan to Spt 1987) all th sampls wr analysd using 25 ml and in priods of high contamination (which coincidd with high sasonal rainfall) th sampls wr anaylsd using 5 ml. On in six of all sampls for th full tim priod wr analysd twic, using both volums. Whn a volum of 25 ml had bn filtrd and mor than 500 colonis wr countd aftr incubation, th count was assignd a valu of 2000 facal coliform colonis pr 100 ml watr. I f 5 ml wr filtrd, and mor than 500 colonis wr sn, a valu of facal coliform colonis pr 100 ml of watr was assignd to th count. Thrfor, th counts of havily contamind sampls ar cnsord to ths uppr limits. Rsults Numbr of watr sampls collctd and analyzd Btwn 21 January 1987 and 26 Fbruary 1988, a total of 4590 childrn undr fiv yars wr visitd at hom in.maho, Nikawritiya and Wariyapola aras and data wr collctd on watr rlatd practics. In th sam aras plus in fcurungala ara, 3185 sampls of stord watr and 1521 sampls of sourc watr wr collctd and analyzd for vidnc of facal contamination from th hom of 856 cass of diarrhoa, 1406 clinic-basd controls and 923 communitybasd controls. For 93 of th sampls of stord watr (2.9%) and 118 (7.8%) of th sampls of sourc watr, th rsults of ths microbiological analyss wr inconclusiv. Ths sampls ar thrfor xcludd form th following analyss. For 85 (2.7 %) stord and 108 (7.1 %) sourc watr sampls th colonis wr too numrous to count and wr allocatd th minimum valus of 2000 or 10,000 facal coliform colonis pr 100 ml of watr according to whthr th volum of watr filtrd was 25 ml or 5 ml. In a fw cass, th information on typ of sourc or watr storag practic was not availabl. On avrag, data wr missing for 2 % of th sampls for ach variabl. Thus numbrs vary slightly, dpnding on th variabl undr considration.

3 Dtrminants of watr quality Trop. Md. Parasit. 41(1990) 91 % housholds Fig. 1 Travl tim to sourcs and man watr consumption of 4439 housholds, Sri Lanka tim of rturn trip (minuts) >30 ky i Man watr quant. -*- Pipd supplis - A ~ Protctd wll -8- Unprotctd sourcs Hand pump Watr sourc choic and watr consumption Svral typs of watr sourc wr usd for drinking. Th most common, usd by 60% of housholds, was protctd shallow wlls, somtims 10 or mor mtrs dp. Ths wr lind with masonry or concrt, with a protctiv parapt and apron, and watr was drawn from thm by buckt. A furthr third (30.8%) usd unprotctd sourcs, usually wlls or watrhols, unlind and oftn lss than two mtrs dp, but somtims surfac watr from rivrs, irrigation channls and larg opn rsrvoirs known as tanks. Only a small minority (6.0%) usd handpumps, mostly installd on borhols. Th borhols with handpumps wr in th cours of installation in th northrn part of th district of Kurungala during th study, as part of th intgratd rural watr supply and sanitation programm startd thr in 1986 by th Dutsch Gsllschaft fur Tchnisch Zusammnarbit (GTZ). By Dcmbr 1987, as th study nard its conclusion, a total of 261 such pumps wr functioning and bing usd by th population. Finally, an vn smallr group (3.3%), who livd in small towns usd pipd watr from public standpips or, in rar instancs, from privat taps. In Wariyapola no borhols wr drilld by th GTZ but a fw handpumps, installd ithr on borhols or, rarly, on shallow wlls ar scattrd in th ara. Th sourcs usd by housholds vary with th sasons, as som traditional sourcs dry up btwn May and Sptmbr. Som wlls provid watr only intrmittntly during th dry sason aftr brif priods of occasional rain. Th data collctd rfr to ach houshold's watr us at th tim of intrviw, but sinc intrviwing continud through a full yar th rsults rflct a typical yar-round pictur. Th findings rflct how vn Kurungala District, on th margins of Sri Lanka's "dry zon", is blssd with an abundanc of watr sourcs. Figur 1 illustrats that on third of all housholds wr abl to collct a containr of watr in fiv minuts or lss, indicating that thir drinking watr sourcs wr lss than 200 mtrs from thir homs and mor than 90% of housholds had a sourc of drinking watr lss than 1 km away. On avrag, th man watr consumption was abov 25 litrs pr capita pr day with only 7.1 % of th housholds using lss than 10 litrs pr capita pr day. Narly thr quartrs of th population (72.7%) usd only a singl sourc for ail domstic purposs, and fwr than on in fiv (18.3%) rgularly usd a sparat sourc for purposs othr than drinking; th rmaindr usd anothr sourc occiasionally. An intrsting finding was that womn rgularly using sparat sourcs wr slightly mor likly to claim that thy washd thir hands bfor prparing a mal (23.8% vrsus 20.4%,X 2 = 4.7,p < 0.05). Of thos using sparat sourcs, mor than half (53.4%) had to walk at last a furthr fiv minuts to obtain drinking watr, and half of ths walkd an additional 10 minuts or mor. Housholds using a sparat drinking watr sourc wr no mor likly than othrs to us handpump or pipd watr for this purpos, but a slightly gratr proportion usd protctd wlls as opposd to unprotctd sourcs. This finding corrspondd with th gnral viw that tast was a major factor in th choic of drinking watr sourc, and that th tast of watr from xisting protctd wlls was ratd highly. Excpt for housholds using pipd supplis, which usd largr quantitis of watr than all th othrs, thr was no significant association btwn th typ of watr sourc or th distanc to it and th lvl of domstic watr consumption (Figur-1). Nor was watr consumption significantly rlatd to th ducation of th child's parnts. Watr quality Sourc watr: Th distribution of facal coliform counts according to typ of watr sourc ar shown in Figur 2. Th prcntag of sampls with organisms found rangd from 48 % for handpump to 82% for pipd watr and 95 % for othr sourcs. Th counts in positivs ar symmtrically distributd on th logarithmic scal; this was confirmd

4 92 Trop. Md. Parasit. 41 Mrtns, T.E..MA. Frnando, T. F. d C. Marshall tal. PIPED (n=31) HAND PUMP Cn=91) PROTECTED UNPROTECTED Fig. 2 Facal coliform counts in spci- WELL WELL mns of sourc watr Cn=792) tn=465) COUNT ' prcnt prcnt prcnt prcnt P r c nt a g P o si -*~ prcantagtt +v«s f~ Qom. man count «v g o m a n c o u nt Fig. 3 Monthly trnd of contamination in sourc watr, Sri Lanka point moving avrag of fittd prcntags positiv and gomtric mans among positivs in protctd wlls at Maho t i V FEB 1987 MAR APR MAY AUG SEP OCT NOV DEC on mor dtaild inspction with th only noticabl dpartur arising from th cnsoring at counts of 2000 and Prcntags of sampls positiv and gomtric man counts among positivs wr takn as sparat masurs of contamination. Corrction for cnsoring carrid out using data from sourc and stord sampls, classifid by typ of sourc and by boiling, suggstd that gomtric mans basd on th cnsord data wr undrstimatd by only 2% to 5%. Thrfor, no corrction for cnsoring was applid in th following analyss. Th trnds ovr tim of th two masurs in sourc sampls ar shown as thr-point moving avrags, adjustd for plac and sourc diffrncs, in Figur 3. This figur indicats th gnral trnds, on avrag for all fiv placs, using as a baslin th facal contamination lvls found in Maho, whr watr analysis was carrid out all yar round; thy do not indicat any trnds at Maho that ar diffrnt from th othr placs. Th most markd fatur was th ris in man facal coliform counts at th nd of th yar, to a pak in Dcmbr (during th north-ast monsoon). Th first dtrmination of th man count (January 1987) was low, possibly bcaus drought conditions had prvaild in lat 1986 and arly In Sptmbr, 1987 thr was an opposit trnd btwn th gomtric man facal coliform (GMFC) count and th prcntag FC positivs: whil th prcntag of positivs incrasd th GMFC count dcrasd. Th two masurs in sourc watr sampls, by typ of sourc and plac ar givn in Tabl 1. Prcntags positiv for facal coliforms wr significantly lowr for pipd and handpump watr, compard with th othr sourcs (p < 0.01). Man counts wr highr for unprotctd sourcs (p < 0.01 for all thr comparisons) but showd no significant diffrncs among th othr sourcs. Spcimns from Maho and Ambanpola tndd to b lss frquntly positiv than th othrs. Man counts wr lowr in Kurungala and Wariyapolathanin Maho and Nikawritiya(p < 0.02) and highr in Ambanpola (p < 0.01). In ordr to stablish whthr contamination rcordd for handpumps was rlatd to ground watr pollution, 60 tubwlls quippd with handpumps and usd by th study population wr sampld aftr strilising th mouth of th pump. Ths sampls wr takn and analysd for fiv conscutiv months from Novmbr 1987 to March Th laboratory tchnician was kpt blind to th origin of thos sampls. Th rsults of ths analyss indicat that out of a total of 216 sampls, organisms wr found in only tn (4.6 %). Ths positiv counts wr in sampls from nin diffrnt tubwlls, ach of which was sampld a minimum of thr conscutiv tims. Furthrmor, amongst th positiv counts only onc a valu of mor than 150 facal coliform colonis pr 100 ml and twic a valu of mor than 50 facal coliform colonis pr 100 ml was rcordd.

5 Dtrminants of watr quality Trop. Md. Parasit. 41 (1990) 93 COUNT PIPED (n=34) prcnt HAND PUMP (n=36) prcnt PROTECTED WELL (n=448) prcnt UNPROTECTED WELL (n=226) prcnt 60 Fig. 4a Facal coliform counts in spcimns of stord watr (watr boild) PIPED (n=60) HAND PUMP Cn = 148) PROTECTED WELL (n=1318) UNPROTECTED WELL (n=736) Fig. 4b Facal coliform counts in spcimns of'stord watr (watr not boild) COUNT prcnt prcnt prcnt prcnt 60 Tabl 1 Prcntag of sourc spcimns with facal coliforms found, and gomtric man (GM) count for thos with coliforms found, by sourc and plac Plac Maho Nikawritiya Kurungala Wariyapola Ambanpola Total s + v + vs + v + vs + v + vs + v + vs + v + vs + v + vs Pipd Supply 5/6 83% 1/2 2/2 15/17 88% 75 1/4 23/31 77% 62 Handpump 5/25 20% 26/31 84% 122 2/4 13/14 93% 68 1/17 6% 47/91 52% 96 Protctd wll 233/249 94% /155 95% /180 97% /1599 7% 74 43/4890% /791 95% 93 Unprotctd sourc 127/135 94% /86 94% /103 96% /79 95% /62 98% /465 98% 203 Stord watr: Whn drinking watr was stord sparatly from watr for othr purposs sampls wr always collctd from th pot in which watr for drinking was stord. Stord watr sampls showd similar trnds ovr tim in facal contamination as wr sn for sourc watr (Figur 3). Figurs 4a and 4b show facal coliform counts in stord watr sampls. Th sparation btwn ngativs and positivs is again clar, as is th ffct of boiling. Tabl 2 givs th numbrs and prcntags of sampls boild and not boild, by sourc and by plac, with th prcntags positiv and th man counts. Th proportion of housholds which boild watr was gratr among usrs of pipd supplis. Th bnfit of boiling is mor apparnt in th prcntags positiv than in th man counts. Th diffrnc in quality of watr from pipd supplis and handpumps, or from protctd supplis in gnral, sms to b only partly prsrvd in th procss of carrying and storag unlss th watr is boild. Comparison btwn sourc and stord watr: 1306 (93%) of 1403 sourc watr sampls includd in th analysis wr paird with stord sampls from housholds using th sam sourc. Figur 5 illustrats th rlationship btwn th counts on a pairwis basis, for all sourcs. Th rarity of low non-zro counts and th apprciabl numbr of pairs whr on sampl is ngativ and th othr positiv should b notd. Th ffct of boiling is also clar. Tabl 3 shows, for ach sourc, th classification of th pairs by th finding of organisms in th two sampls. Among boild sampls, th high proportion showing a chang from a positiv sampl at sourc to a ngativ sampl from th stord watr is striking. Among sampls claimd to b unboild, th highst proportion of ngativ stord sampls

6 94 Trop. Md. Parasit. 41 Mrtns, T. E., M.A. Frnando, T. F. d C. Marshall t al. watr not boild watr boild Fig S * 1295 sourc counts * 1295 sourc counts Comparison of paird spcimns of sourc and stord watr: ffct of boiling th watr on facal contamination stord counts Tabl 2 Sampls of stord watr, classifid by sourc and whthr it was claimd to b boild or not, with prcntags positiv for facal conforms, gomtric man (GM) counts among th positiv spcimns and confidnc intrvals* (Cl) on th gomtric mans. Boild no. spcimns prcnt + v + vs 95%CI Not boild no. spcimns prcnt + v + vs 95% Cl Pipd supply 34 53% % Handpump 36 42% % "Th confidnc intrvals ar basd on th within-cll varianc of th log counts. Protctd wll % % Unprotctd sourc % % paird with ngativ sourc sampl was from handpumps. Among handpump sampls howvr, a substantial proportion of th pairs changd from ngativ at sourc to positiv whn stord. Conditional logistic rgrssion analysis of th discordant pairs confirmd a strong boiling ffct (p < 0.001), and among unboild sampls a strong contrast btwn handpump watr quality compard with protctd wlls and unprotctd sourcs (p < 0.001). Othr factors affcting stord watr quality: As shown abov, among housholds whr th rspondnt claimd that th watr was boild, th prcntag of positiv sampls as wll as th avrag lvl of contamination in th sampls wr much lowr compard with sampls takn from othr housholds. Among unboild sampls th watr was lss frquntly contamind and th lvl of contamination among positivs was lowr if it had bn drawn from a handpump. Th following additional factors wr associatd with lowr lvls of contamination in stord watr: Us of diffrnt vssls for collction and storag. Among boild spcimns, 43% of th sampls wr contamind compard with 57% whn th sam vssl was usd. Without boiling, th figurs wr 84% and 94%. Not surprisingly, us of a diffrnt vssl was mor common whn th watr was boild, at 37% compard with 3% without boiling. Storag insid th hous. With watr from unprotctd sourcs, 96% of spcimns from outsid storag wr contamind, compard with 83% from storag insid. Th most common storag arrangmnt was insid with a covr; 87% of boild and 75% of unboild spcimns cam from watr stord this way. Thr was no vidnc that failur to us a covr was associatd with contamination,'though vry fw housholds stord watr outsid, uncovrd. Us of non-arthnwar containr for storag. 58% of sampls wr from arthnwar vssls. Most of th rst wr from largr-sizd mtal or plastic containr and contamination was marginally lss in ths. A fw (126).sampls wr from a varity of othr typs of vssl, such as bottls, kttls tc., and coliforms wr found in ths about 15 % lss frquntly. Most of th sampls in th last group wr boild, but th diffrncs in contamination hld for both boild and unboild watr. Storag for a longr priod, for unboild watr. Whn th sam vssl was usd (s abov) and was covrd during storag, thr was slightly lowr contamination (about 4% lss positivs) in spcimns that had bn collctd mor than 12 hours bfor sampling, compard with thos collctd mor rcntly.

7 Dtrminants of watr quality Trop.Md.Parasit.41(1990) 95 Tabl 3 Watr boild stord Paird spcimns, cross-classifid by positiv or ngativ for facal coliforms in sourc and stord watr spcimns Ys Sourc -v + v No Sourc -v + v pipd supply -v v Watr sourc handpump protctd unprotctd wll sourc -v +v -v +v -v +v Tabl 4 Handling and storag Good Middl Poor Modl-basd stimats of prcntag of spcimns with facal coliforms for wtr handld and stord in diffrnt mannrs. % + v % -I- v % + v pipd supply 32% 38% Watr sourc handpump 20% 38% protctd wll 40% 56% 93% unprotctd sourc "Good"-boild, diffrnt vssl for storag, stord insid; "Middl"-not boild, diffrnt vssl for storag, stord insid; "Poor"-not boild, sam vssl for storag, stord outsid. 39% 82% 98% Th ovrall contribution of four factors togthr, sourc, boiling, us of th sam vssl and mannr of storag, on th prsnc of facal contamination in th sampls of stord watr was xplord by logistic rgrssion. Apart from sourc, th ordr of importanc of th factors was boiling, us of diffrnt vssl for storag, and storag insid; storag insid was statistically significant only for watr from unprotctd sourcs. Th modl also indicatd that sampls from th community survys wr lss oftn contamind. Tabl 4 shows prdictd proportions of sampls contamind whn catgorizd in what appard to b th good, middl and poor ways. Th good and poor ways wr adoptd by rlativly fw housholds in this survy; 9% wr in th "good" catgory and 11 % in th "poor" (4% and 10% rspctivly among usrs of handpumps). Th tabl indicats th xtrms of what might b achivd, with prcntag ranging from 30% to 98 %, undr th assumptions of th modl. W found no vidnc that th tim of th day at which th collction took plac or th tim takn to carry out th watr collction had any ffct on stord watr quality. Discussion On avrag, man watr consumption was abov 25 litrs pr capita pr day and was unrlatd to th typ of sourc or th distanc to it or th ducation of th child's parnt. Although it is, prhaps, a countrintuitiv finding, this corrsponds with th rsults of studis lswhr in th dvloping world (Whit t a!., 1972; Fachm t a!., 1978), and in Sri Lanka (Pinnawala and Hrath, 1986). Evn during th drought th tim to rach a sourc of watr did not diffr substantially from normal conditions, xcpt for a minority of th housholds. Environmntal microbiology was prformd using th mmbran nitration tchniqu, which is wll standardizd and yilds snsitiv and spcific rsults (Chsbrough, 1984; WHO, 1984). Quality control chcks confirmd to som xtnt th rliablity of th mthod in this tropical stting with 97% agrmnt btwn diffrnt nitrations of th sam sampl, 8.8% disagrmnt btwn sampls of th sam origin and 100% spcificity on stril watr. In this study th lvl of facal contamination occurring at th watr sourc appard to dpnd on th typ of sourc, rainfall and, to a lssr xtnt, on gographical location. Ths rsults confirm th findings of a numbr of othr studis conductd in a wid varity of sttings (Barrl and Rowland, 1979; Wright, 1986; Blum tal., 1987). In gnral, th proportion of sampls in which FC colonis wr found, and th lvl of contamination of watr as masurd by th gomtric man FC count wr both vry high in comparison to WHO Guidlins for Drinking Watr Quality (WHO, 1984). Th sourcs which providd drinking watr closst to ths standards wr public handpumps first, followd by th pipd supplis. Handpumps providd watr of th bst quality throughout th yar. Whn th mouth of th tap was strilisd lss than 5 % of sampls showd facal contamination at low lvls. Howvr, whn watr was drawn in th usual mannr around 50% of sampls wr found to b contamind. Ths rsults suggst that ground watr contamination is ngligibl if it occurs at all, but that substantial pollution of watr occurs at th priphry of th systm. Public handpumps ar th sit of intnsiv human and animal activity and both animal and human contamination of th mouth of th tubwll probably occurs, particularly via contamind hands. Amongst th 50% of sampls which showd vidnc of facal contamination, th avrag lvl of pollution was as high as th man lvl in pollutd sampls from protctd shallow wlls. Protctd wlls ar a traditional sourc of drinking watr in Sri Lanka; thy ar widly usd by mor than 50% of th population and ar rgardd as providing watr which is "tasty" and pur. About 45 % of ths wlls ar public and wr dug by th govrnmnt. Unprotctd sourcs includ

8 96 Trop. Md. Parasit. 41 Mrtns, T.., MA. Frnando, T.F.dC. Marshall tal. shallow watr hols, usually ownd privatly and surfac watr. Th watr providd by ths sourcs rvald high lvls of contamination in 96 % of th sampls tstd. Thr wr sasonal variations in th lvl of pollution, spcially in watr drawn from th traditional sourcs, including protctd wlls. Th gomtric man of facal coliform counts pakd in Dcmbr during th monsoon rain whras th proportion of positivs pakd arlir, at th bginning of th rain in Sptmbr. Pollution which paks during th arly rain is usually attributd to run-off and is most likly to affct unprotctd watr hols. Contamination of traditional sourcs, howvr, lastd until long aftr monsoon rain had stoppd in 1987, spcially in unprotctd sourcs. Anthropological invstigations in Sri Lanka suggst that this sasonal pattrn of watr pollution is common knowldg (Nichtr, 1988). This sasonal pattrn suggsts that surfac watr pollution has a mor important ffct than ground watr pollution on th quality of watr providd by unprotctd watr sourcs. This has important policy implications, sinc it suggsts that watr quality could b gratly improvd simply by th construction of a protctiv hadwall and drainag apron around th unprotctd sourcs which ar usd by approximatly on third of th population. Th factors that strongly influncd th quality of stord drinking watr wr (i) th typ of sourc from which it was drawn, (ii) whthr or not th houshold claimd to boil th watr, and (iii) th mthod of storag. Whthr or not th watr was claimd to b boild appard to b th most important modifir of stord watr quality although boiling was practisd by only 25 of th population using handpumps and traditional sourcs and 35% of pipd supply usrs. Whil it may not sm suprising that boiling affcts watr quality, this finding hlps to confirm th accuracy of th information givn by th rspondnts during th intrviw. Howvr, about 50% of th sampls wr still positiv aftr boiling, probably bcaus watr was oftn allowd to cool in a vssl for svral hours bfor consumption. For unboild sampls, th contamination of stord watr was similar to that of th sourc watr xcpt for th unprotctd sourcs whr storag appard to hav dcrasd th lvl of contamination. Th ffct of th typ of sourc on th proportion of sampl of stord watr which wr contaminatd may b summarisd in th following way. Among thos who boild or stord th watr insid th hous and usd a diffrnt vssl for storing purposs, th proportion of sampls contamind from handpump was much lss than that of all protctd and unprotctd traditional sourcs. Howvr, if th watr was kpt unboild, stord outsid or uncovrd and th sam vssl was usd for collction and storag, thn th supriority of handpumps and pipd supplis ovr th protctd wlls was much rducd, but rmaind substantial ovr th unprotctd sourcs. Th rsults prsntd abov suggst that, whil improvd sourcs suffr lowr lvls of facal contamination, this ffct is rducd whn th watr is stord. Howvr, th microbiological analyss prformd provid information only on indicators of facal contamination. Thy tll us littl about th lvl of contamination with ntropathogns. It might rasonably b argud that it is contamination of watr at th sourc which is most important in th transmission of diarrhoal disass (Fachm t al, 1978). At any givn tim, contamination of watr within th houshold is unlikly to lad to infction with ntropathogns unlss a houshold mmbr is alrady infctd. Morovr, pathogns prsnt in th houshold ar likly to b transmittd btwn th houshold mmbrs anyway, by othr routs. Sourc watr, on th othr hand, may b xposd to contamination by a much largr population, spcially whn th sourc is public or shard by svral housholds, incrasing th probability of contamination with pathogns lading to infction. Such a situation may wll occur in th district of Kurungala whr only a small minority of housholds own thir own wll. About 50% of th population draw thir drinking watr from public wlls whil th rmaining 40% of th population dpnd on facilitis ownd by othr popl for drinking watr (Pinawala and Hrath, 1986). Thus changs in th pathogn contnt of watr during its collction, transport and storag (without boiling) may dpnd upon diffrncs in th survival charactristics of ach pathogn prsnt. Indicators of facal contamination may not truly rprsnt th prsnc of ntropathogns in th watr sinc domstic facal contamination with normal intstinal flora can still occur and will b dtctd by th mthod. In ordr to confirm this hypothsis, a usful addition to th tchniqu of mmbran filtration for th dtction of facal coliforms would thrfor b th dtction of ntropathogns, such as Shiglla spp and Salmonlla spp, in stord watr. Such tchniqus rquir largr volums to b filtrd and spcial growth mdia, and hav bn usd in a fw studis only (.g. Singr t al., 1975). This study suggstd that ntropathogns such as Samonlla spp could b isolatd from drinking watr at sourc watr which othrwis fulfilld th standards in rgard to total and facal coliform counts. Rfrncs Barrl, R. A. E.. M. G. M. Rowland.Th rlationship btwn rainfall and wll watr pollution in a Wst African (Gambian) villag. J. Hyg. 80 (1979) Blum. D.. S.R.A. Huttly. J. I. Okoro. C. Akujobi. B. R. Kirkwood, R. G. Fachm: Th bactrial quality of traditional watr sourcs in north-astrn lmo Stat, Nigria. Epidm. Infct. 99 (1987) Cairncross. S.. J. L. Cliff: Watr us and halth in Muda, Mozambiqu. Trans, roy. Soc. trop. Md. Hyg. 81(1987) Chsbrough. M.: Mdical laboratory manual for tropical countris. Vol. 2. Tropical Halth Tchnology. Doddington, U.K. (1984) Fachm. R. G.. E. Burns, S. Caimcross.A. Cronin, P. Cross. D. Curtis. M. Khalid Khan, D. Lamb. H. Southall: Watr, halth and dvlopmnt: an intrdisciplinary valuation. Tri-Md. Books, London(1978)129 McCullagh, R., J. A. Nldr.Gnralizd linar modls, Chapman & Hall, London (1983) 123 Mrtns, 7. E., S. N. Cousns, M. A. Frnando, B. R. Kirkwood, F. Mrkl, R. Kort, R. G. Fachm: Halth impact valuation of improvd watr supplis and hygin practics in Sri Lanka: background and mthodology. Trop. Md. Parasit. 41(1990a) Mrtns, T..., M. A. Frnando, S. N. Cousns, B. R. Kirkwood, T. F. dc. Marshall, R. G. Fachm:Childhood diarrhoa in Sri Lanka: a cas-control study of th impact of improvd watr sourcs. Trop. Md. Parasit. 41 (1990b) Nichtr, M.: From "aralu" to ORS: Sinhals prcnptions of digstion, diarrhoa, and dhydration. Soc. Sci. Md. 27 (1988) 39-52

9 Dtrminants of watr quality Trop. Md. Parasit. 41(1990) 97 Pinawala, S. K., H. M. D. R. Hrath: Study of watr collction and us Dr. T. E. Mrtns in slctd communitis of Kumngala District. Rport to GTZ. Dpartmnt of Epidmiology and Population Scincs. Dpartmnt of Sociology Un.vcrity of Pradmya (1986) ^ Schoo 0 P f Hygin and Tropical Mdicin Rajaskaran. P.. P-XDutt. K.A. Jtfaro/i: mpactofwatrsupplyon K PP l Strt, London, WC1 E7HT.U.K. th inadnc of diarrhoa and shigllosis among childrn in rural communitis in Madurai. Indian J. md. Rs. 66 (1977) Schnidr, R.., M. Shiftman, J. Faignblum.Th potntial ffct of watr on gastrointstinal infctions in dvloping countris. Amr. J. clin. Nutr. 31 (1978) Singr, F., R. Baylt, M. Chapat: Salmonlla isols ds aux d'alimntation. Rv. Epidm. Md. Soc. Sam Publ. 23 (1975) Whit. G. F., D. J. Bradly, A. U. Whit: Drawrs of watr: domstic watr us in East Africa. Univrsity of Chicago Prss, Chicago (1972)128 WHO:Guidlins for drinking-watr quality. Vol. I, WHO, Gnva (1984) Wolyntz, M. S.: Maximum liklihood stimation from confind and cnsord normal data. Applid Statistics 28 (1979) Wright, R. C..Th sasonality of bactrial quality of watr in a tropical dvloping country (Sirra Lon). J. Hyg. (1986) 75-82