BACTERIAL QUALITY OF RAINWATER IN SELECTED COMMUNITIES IN IMO STATE, NIGERIA

M any rural c om m unitie s in Im o S tate , Easte rn N ig e ria do not h ave ac c e ss to potable w ate r. R ainw ate r h as be e n a m ajor sourc e of w ate r supply in th e se are as m ainly during th e rains. Bac te rial q uality of h arve ste d rainw ate r from th re e c om m unitie s (U m unum o, Eg be m a, Ih iag w a) w e re de te rm ine d. R ainw ate r sam ple s w e re h arve ste d dire c tly , from z inc roof, th atc h e d roof and from asbe stos roof, at diffe re nt pe riods of th e rains – M ay (be g inning of rains), July (pe ak of rain) and O c tobe r (e nd of rains). S tore d rainw ate r from z inc roof in U m unum o w as also e x am ine d. T h e bac te rial c ount w as h ig h at th e be g inning of rains w ith rainw ate r c olle c te d from th atc h e d roof in Eg be m a sh ow ing th e h ig h e st (7 .4 x 10 c fu/100m l) value . T h e total c oliform and fae c al c oliform ( ^6_ `%aYb c#dG`%a dGe]` fGg d ) c ounts rang e d h ig h e st at th e be g inning of rains be tw e e n 10 – 36 c fu/ 100m l and 1 – 5 c fu/100m l re spe c tive ly . T h e total bac te rial c ounts, total c oliform c ounts and fae c al c oliform c ounts of store d rainw ate r w e re h ig h e st in sam ple s from unde rg round tank . S am ple s c olle c te d dire c tly at th e pe ak and e nd of rains in all th e c om m unitie s m e t th e W H O standard for drink ing w ate r. U sing a statistic al m ode l, at a = 0.05, th e null h y poth e sis, w as re je c te d for m e th ods and pe riod of c olle c tion, w h ile loc ation of c olle c tion w as ac c e pte d, h e nc e only pe riod and m e th od of c olle c tion of rainw ate r affe c te d th e bac te rial q uality . hOi-j kml;n o*p q Bac te rial q uality ; C oliform s; C ontam ination; H andling ; H arve sting ; P otable ; R ainw ate r; W ate rborne .


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Estud.Biol., v. 28, n.63, p. 51-59, abr./jun.2006 t !u !v w (v u !v ©x y z { iz v | F} ©6z T F D y F F D Rainwater harvesting (RWH) has become a global practice in order to meet the growing challenges of water supply.Many countries of the world have adopted rainwater as a major alternative water supply since underground and surface water bodies are under pressure of industrial pollution.
Imo State in Eastern Nigeria has a large population of more than 7 million people with more than 70% of the entire populace living in rural areas where there are no supply of pipeborne water.In the urban areas where portable water supply is epileptic, people resort to rainwater mainly during the rains.A mean intensity of 180 -220cm of rainfall is experienced in the Southern part of Nigeria (1).No source of water supply for human consumption can be assumed to be free from pollution.However, rainwater, if well handled, is the purest natural water (2).Both natural and anthropological pollution affect water quality (3).Polluted water has been important vehicle for the spread of diseases.It has been estimated that about 50,000 people die daily world-wide as a result of water-borne diseases (4).
Many rural communities in Imo state practice domestic roof rainwater harvesting (DRWH).This is done between May to October each year with underground and surface tanks serving as storage facilities.Rainwater harvested from zinc and Aluminum roofs serve as drinking water without further treatment in many rural areas in Imo State while water from thatched roofs is used for other domestic purposes, but serve as drinking water in some homes in Botswana (5).This may lead to diseases as poor water quality is considered a major cause of water-borne diseases in remote areas (6).This study was aimed at examining the bacterial quality of rainwater, a major source of water supply in many rural communities in Imo State, Nigeria with the view of evaluating its health implications.The samples were tagged accordingly: SA -Samples from Egbema, Orlu Z one SB -Samples from Umunumo, Okigwe Z one SC -Samples from Ihiagwa, Owerri Z one SD1, SD2, SD3 represent samples from PV C water tank, metallic water tank and underground water tank respectively.
Microbiological Analyses were conducted within 6 hours of collection.
Total Bacterial Counts: The pour plate method using nutrient agar was used.Plates were prepared in duplicates and incubated at 37 0 C for 48 hrs.The numbers of colonies were counted and the colony forming units per 100ml (cfu/100ml) determined.
Total Coliform Counts: Coliform counts of the samples were determined using membrane filtration technique which used absorbent pads saturated with MacConkey broth in Petri dishes prepared in duplicates and labeled correctly.The membranes were incubated at different temperatures of 37 0 C and 44 0 C for 24 hrs for presumptive coliform count and faecal coliform (Û 1Ü qÝ YÞ iß !à Vá Ý YÞ iá â Ý Yã Tä &á ) count respectively.å Ñ 7× 9Ñ 5Ê 7Ú TÑ 5Ê 7Ð ¢× 9Ï EØ Ò × RÏ Ù $Ú TÊ 7Ú The goodness of fit which used chi-square was employed because of the nature of data generated.The null hypothesis assumed that bacterial load of rainwater is not affected by: location (place), period (time), as well as, method (mode) of harvest.In each case, if the chi-square table was highly significant, at 99.95% confidence interval, the null hypothesis was accepted, otherwise rejection of the null hypothesis.

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The bacterial count of rainwater harvested at the beginning of rains show that total bacterial count was of the order 10 3 , ranging from 0.39 x 10 3 -7 x 10 3 cfu/100ml.
Bacterial count of rainwater harvested at the peak of rains is shown in table 2. The total bacterial count decreased and was in the order of 10 2 .There was reduction in total coliform count and Û iÜ (Ý EÞ yß Bà Fá Ü (Ý Þ á â íÝ ã 2ä &á .Feacal coliforms ranged within 0 -4 cfu/100ml while Û 1î «Ý Yã ¢ä á had 1.0 cfu/ 100ml as the highest recorded value. The data in table 3 shows the bacterial count of rainwater at the end of rains.As at the peak, the total bacterial count was of the order 10 2 .Coliforms were recorded in all the samples except in SC I , but in decreased number (1 -3 cfu/ 100ml).Û 1Ü qÝ YÞ iß !à Vá Ü qÝ YÞ iá â Ý Yã ¢ä á was < 1.0 cfu/100ml.The bacterial count of stored zinc-roof rainwater shows that it ranged between 1.28 x 10 2 to 2.01 x 10 2 cfu/ 100 ml (Table 4).Total coliforms of 36, 41 and 97 cfu/100ml were recorded in SDI, SD2 AND SD3 respectively.Only samples from under ground water tank had 1.0 cfu/100ml of feacal coliform (Û 1Ü qÝ YÞ iß !à Vá Ý YÞ ¥á â Ý Yã ¢ä á ).ï È 2Ú ð ¥Ï 6Ñ 7Ú å Ñ 7× 9Ñ 7Ê 5Ú TÑ 7Ê 5Ð T× 9Ï EØ Ò y× 9Ï Ù RÚ ¢Ê 7Ú The data in tables 5, 6 and 7 show the statistical analyses of bacterial load of rainwater from different locations, harvested at different periods and by different methods respectively.In each case, the null hypothesis which stated that bacterial count of rainwater was not affected by location of collection, period, and method of collection respectively was tested using chi-square test at 99.95% confidence interval.The null hypothesis was accepted in table 5 hence location of collection did not affect the bacterial count of rainwater.The highly significant figures rejected the other hypothesis at degree of freedom 6 and 99.95% confidence interval.

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The results of the bacterial quality of rainwater from selected communities in Imo State, Nigeria reveal that rainwater collected at the commencement of rains did not meet the World Health Organization (WHO) standard for drinking water.Such water however could be used for laundry and toilet flushing.The bacterial load of water determines its portability.The presence of ± £² §³ `%µ G ¶ @• T³ `%• 3³ `¹ º • indicated faecal contamination.The rainwater at the peak and end of rains showed standard bacterial quality.The high bacterial and coliform counts in water samples at the beginning of rains is attributable to feacal contamination from humans, reptiles, birds, etc.Many investigations show that the purest form of natural water are snow and rainwater (7).The method of collection and storage however determine this attribute.The best method of collecting rainwater is the direct method since it does not come in contact with any surface except the atmosphere.However, zinc or Aluminum roof method is good, but asbestos roof should be discouraged because of Lead Solvency (8).Poor handling has been established to be the major cause of secondary contamination of rainwater (9,10).Water from the underground storage tank had the highest number of both bacterial count and faecal coliforms.The reason is not far from the above affirmation -poor handling such as non-washing of the tanks before the rains, and again long storage period which could as well lead to growth of microorganisms (7).
Rainwater has served as a source of water supply in both rural and urban areas in the developed and developing countries.Since the supply of pipe-borne water to rural areas by Government in Imo State is tasky, she can device means of harnessing this naturally-purified-water by maintaining and improving its hygienic quality through proper collection and storage.Suggestions have been given that roof maintenance, screen installation, first flush devices, chlorination, boiling