The Relationship between Bacteriological Quality of Dug-Wells & Pit Latrine Siting in an Unplanned Peri-Urban Settlement: A Case Study of Langas – Eldoret Municipality, Western Kenya

This study was carried out in Langas, an unplanned peri-urban settlement in Eldoret municipality in western Kenya. The objective of the study was to determine the bacteriological quality of dug-wells vis-a-vis pit lat rine siting. Water samples were collected from each dug-well and the distance between each dug-well to the nearest pit latrine was measured. The MPN technique was used to determine number o f faecal colifo rms. The mean d istance between dug-wells and pit latrines was 19.664m. 34% of samples had total coliform counts ranging from 0-99TC/100ml and 14% had over 1100TC/100ml. 82% of dug-wells had faecal colifo rms ranging from 0-99FC/100ml while only 2% had 1100FC/100ml. A significant but weak indirect (negative) association between pit latrine distance and level of faecal contamination was detected using the chi square test. That is, as distance between pit latrine and dug-well increases, the Faecal Coliform count decreases. This could be interpreted as decreasing distance increases the chances/risk for dug-well contamination to occur. Using the Linear Regression model, the minimum d istance for dug-well contamination not to occur through latrine seepage was found to be not less than 38m.


Introduction
It is often said that good sanitation improves the quality of life by reducing commun icable diseases like childhood diarrhoeas. It also is known that "water is life" and "sanitation is health" However, good sanitation facilities alone are unlikely to decrease the risk o f disease transmission unless accompanied by good hygiene practices. This leaves no doubt that the relationships amongst water supply, sanitation and human health are linked intimately [1].
It is a well-known fact that in the largest cities in Africa, water and san itat ion serv ices are hard p ressed to meet the needs of the expanding population [2]. In Eldoret municipality in Western Kenya, an inadequate supply of piped water in peri-urban areas cannot go unnoticed, especially in Langas estate where this study was focused. The state of affairs in Langas is indicated by the springing up of dug-wells, both protected and unprotected apparently without any consideration of their sit ing with respect to pit latrines. The ob jective of this study was to determine the degree of faecal pollution of dug-well water and to investigate whether it was correlated to the distance between dug-wells and pit latrines. We hypothesised that dug-well water in Langas is not contaminated with faecal matter due to latrine seepage. This null hypothesis was adopted because an earlier study in the same area by Asheesh et al. [3] found no correlation between dug-well water quality and the distance of dug-wells fro m p it latrines. The chi-square test was used to test this hypothesis.
The study involved detecting both total and faecal colifo rms in water samp les fro m dug-wells. Total coliforms are a heterogeneous group that includes lactose-fermenters such as Enterobacter cloacae and Citrobacter freundii, which can be found in feces and in the environment as well as in drinking water containing relatively high concentrations of nutrients. Faecal coliforms are thermo-tolerant bacteria that are able to ferment lactose at 44-45 o C; the group includes the genus Escherichia and some species of Klebsiella, Enterobacter and Citrobacter. In most circu mstances, concentrations of thermo-tolerant organisms are directly p roportional to that of E. coli whose source in water supplies must always be faecal contamination [4].

Study Area
The study was conducted in Langas, unplanned peri-urban settlement in Eldoret Municipality. It is situated southwest of Eldoret town, about 5km fro m the town centre along the Eldoret-Kapsabet road.
Langas is divided into 4 blocks. The blocks are further subdivided into about 1811 plots. Each plot has between 1 and 30 households. Each household has an average of 6 occupants and occupies an average area of 10 square meters. Very few houses have electricity and most of them are semi-permanent.
The main sources of domestic water are dug wells, wh ich are communal (shared among several households in a plot). There were a total of one hundred (100) dug-wells in Langas at the time of th is study. The main method of excreta disposal is through use of the traditional pit latrine. The area has a high water table.

Study Design
The study involved determining the bacteriological water quality of dug-wells in relation to the siting o f p it latrines, followed by thereafter testing and describing the relationship between the two variables.
A convenient sample of fifty (50) hand-dug wells evenly distributed in Langas was chosen for this study. This sample size represents 50% of all the dug-wells in the study area.
All wells samp led met each of these inclusion criteria: fully protected; the rope for drawing water always left suspended in the well at all times except during the drawing of water. Also, there were to be no obstacles like buildings blocking the straight line fro m dug well to the nearest pit latrine; and, the well must not have been chlorinated in the past three months.
A grab samp le was collected fro m each dug-well. A string, wiped with a disinfectant (i.e.70% methylated spirit) was tied around the neck of each sterile samp ling bottle which was then lowered into each well without it touching the inside walls of the well. Each samp ling bottle was immed iately capped, without the hands coming into contact with its mouth, upon withdrawal of the water sample fro m the well. The samp les were labelled with date, time, samp le serial nu mber, and the distance of the well fro m pit latrine.
The bottled water samp les were put into polythene bags and then transported to the laboratory. Each polythene bag contained ice packs to prevent mu ltiplication of microorganis ms. Temperatures in the polythene bags ranged fro m -2 ○ C to 8 ○ C. A ll samples were transported to the laboratory with in 1 hour after collection. Samples were maintained at similar temperatures in the laboratory refrigerator before analysis. All samples were analy zed within 24 hours after collection. Measurements of distance were taken fro m the foot of the latrine superstructure to the perimeter of the mouth of the well.
Laboratory analysis was performed following the procedures of Collins, Lyne & Grange [5]. Co liforms were detected by the MPN method as described in Co llins, Lyne & Grange [5]. All the tubes that showed turbidity (i.e. reaction) and gas production constituted positive reaction that indicated presence of coliforms.

Statistical Anal ysis
The null hypothesis for this study was that the siting of pit latrines in Langas does not contribute to the faecal contamination of dug-wells due to latrine seepage.
The chi-square test was then used to test a possible association between dug-well contamination and distance to pit latrine. The chi square for linear trend was also used to determine if the association between dug-well contamination and distance to pit latrine changes as the distance increases. We considered a p-value less than 0.05 as statistically significant. We also estimated Spearman's correlation coefficient and fitted a linear regression line to estimate the dependence of faecal coliform counts on distances between dug-wells and pit latrines.

Results
This section presents results from the bacteriological analysis of water samples and measurements fro m dug-wells to the nearest pit latrines. Ten per cent (10%) of the dug-wells were located less than 10 metres fro m the pit latrines, while 46% and 40% were located 10 metres to 19.99 met res and 20 metres to 29.99 metres fro m pit latrines respectively. On ly 4% were p laced at 30.06 metres or above [ Table 1]. Thirty four per cent (34%) of the samp les had total coliform counts ranging fro m in an Unplanned Peri-Urban Settlement: A Case Study of Langas -Eldoret M unicipality, Western Kenya 0-99TC/ 100ml and 14% had over 1,100TC/ 100ml. Eighty two per cent (82%) of the samples had faecal co liforms ranging fro m 0-99FC/ 100ml wh ile only 2% had 1,100FC/ 100ml [ Table 2].
The mean distance between dug-wells and closest pit latrine was 19.664 metres while the mean faecal coliform count was 85.41FC/ 100ml (table not shown).   The result of chi-square test for independence between the distance of dug-well fro m nearest pit latrine and amount of Faecal Coliforms gave chi-square = 9.652 and a p-value of 0.022. This showed a significant association between the variables ( Table 3).
The analysis of a further test of chi-square to determine if linear trends exist between the distance of dug-well fro m nearest pit latrine and amount of Faecal Coliforms found in them is shown in table 4. We found a X 2 =3.89 and p-value = 0.04. Th is indicated a linear trend existed between dug-well and nearest pit latrine and that the odd ratio of a dug-well being contaminated in terms of amount of Faecal Coliforms reduced as distance between the dug-wells and nearest pit latrines increased.

Linear Regression Model for Distances between dug-well and nearest pit latrine and Faecal Coliforms/100ml
Using distances between dug-well and nearest pit latrine as independent variable and amount of Faecal Coliforms in dug-wells as the dependent variable, we obtained the linear regression line in equation (1) c= 130.141 -3.383d (1) where c= faecal coliform count and d =distances between nearest pit latrine and dug-well.
The test of significance of the coefficient of the distance produced p-value = 0.074 while the test of significance of the constant gave p-value=0.001.
The fitted regression line showed that every increase of one metre in distance between nearest pit latrine and dug-well will cause a decrease of 3.38FC/ 100ml of contamination in the dug-wells. [ Figure 1] More so, fro m equation (1) above, the fitted regression line gave the distance (d) d = 130.141/ 3.383 = 38.47 metres (2) by setting amount of faecal coliforms (c) to zero. That is, on the average, the minimu m d istance for such contamination not to occur is approximately 38 metres. Any distance below 38 metres between nearest pit latrine and dug-well will certainly cause contamination to occur.
The result also showed that for a dug-well placed side by side (within less than one metre perimeter) with a pit latrine, the level o f contamination in terms of Faecal Co liforms could be as high as 130FC/ 100ml. Rather than using Pearson's correlation coefficient, we used Spearman's rank correlat ion coefficient because the assumption of normality has been violated in the data distribution. The distribution of faecal coliform counts in the dug-wells followed an exponential p rocess. We obtained Spearman's rho = -0.275 with p-value = 0.050 and the scatter plot of the association between the variables with a fitted linear reg ression line is as shown in Figure 1. We used only 49 samp les for both the regression and correlation analysis by removing sample nu mber 10 fro m the analysis because its faecal colifo rm count was estimated to be above 1100FC/ 100ml. We considered this as an outlier.

Association between Dug-Well Contaminati on and Pit Latrine Siting
In this study, we detected that a significant association existed between distances from dug-wells to nearest pit latrine and that this association between level of dug-well faecal contamination and d istance to nearest pit latrines was indirect. For every one metre increase in distance between dug-well and pit latrine, there was a corresponding decrease of 3.38FC/100ml in terms of contamination.
In a previous study [3] association was not found between dug-well water bacterio logical quality and the distance of dug-wells to nearest pit latrines. They attributed the lack of association to the many possible confounders, e.g. hygiene behaviour, area geomo rphology and the presence of other contamination sources. They suggested that once measures to control these other sources of contamination and confounders are in place, the role of latrines in the contamination of well water could then be quantified. However, in the same study, the investigators found that bacteriophages introduced into a latrine that was 31.5m fro m a well were detected 48 hours later in another well that was 63m away. This suggests that there is seepage fro m p it latrines to well water, despite the fact that no correlation was found between the two variables under investigation.
In our study, we detected an indirect association between level of dug-well faecal contamination and distance to pit latrines. Theoretically, if dug-wells and pit latrines were placed side by side (i.e. within one metre perimeter), the level of faecal contamination would be as high as 130FC/ 100ml. The null hypothesis that pit latrine siting does not contribute to faecal contamination of dug-wells in Langas, therefore, is disproved.
In the current study, we controlled for contamination of dug-wells due to surface run-off by selecting only protected wells for investigation. Thus, in the absence of any other uncontrolled factors (such as poor hygiene practices by dug-well users), at less than 38.5m, there is a significant possibility that dug-well water is contaminated by nearby latrines through underground seepage in the Langas. Conversely, at distances greater than 38.5m, dug-well contamination by faecal co liforms through latrine seepage is not expected. It should therefore be assumed that this is the minimu m safest distance between dug-wells and pit latrines in Langas.
This study has also established that the mean distance fro m pit latrines to dug-wells in the Langas area was 19.664m, which is quite lo w co mpared to the WHOrecommended standard of at least 30m [6] and our detected safest distance of approximately 38 metres.
Out of the fifty (50) water samples taken, 98% were found to have faecal coliforms ranging fro m 3FC/100ml to 1100+FC/100ml. Only 2% of samp les had no faecal colifo rms. These findings were similar to the earlier findings by Kimani and Ngindu [7] wh ich discovered that 3% of samples had no faecal contamination whereas 97% had. Kimani and Ng indu [7] had also found out that 89% of the area residents in Langas rely on dug wells as their major source of domestic water and co mpared to the WHO recommended bacteriological standards of drinking water quality (i.e. a maximu m of 1FC/100ml), our findings in Langas are worriso me.
Our study showed that most dug-wells were very close to pit latrines. In a 1989 study by German Environ mental Consultants in Langas, 54.1% of the wells were found to be less than 20m away fro m the pit latrines [2]. In yet another study at the same area, 38% of latrines were estimated to be situated less than less than 15 and most dug-wells (about 59%) were estimated to be at a d istance between 15m and 30m fro m the pit latrines [7]. These previous results were in agreement with the findings our present study, which found out that 56% o f dug-wells were placed at a d istance range of less than 20 metres to pit latrines.

Recommended Gui delines and Legal Framework for the Prevention of Underground Water Pollution
According to the WHO guidelines, obvious causes of contamination should be removed fro m the catchment area, and special attention given to the safe disposal of hu man excrement. Dug-wells should be protected by lining and covering, diverting surface drainage, preventing erosion and paving the surrounding area. Fencing should restrict human and animal access and the source should be so designed that fouling does not occur when water is drawn [8].
In addition to the WHO guidelines, there are legal provisions in Kenya's public health laws addressing the same issue. The Water Act Cap 372, section 158(1) states that "any person who by any act or neglect, causes any source of water supply, the water fro m which is used or is likely to be used for human consumption or domestic purposes, or for manufacturing food or drink for human consumption, to become polluted, or to be likely to be polluted, shall be guilty of an offense" [9]. Thus, the law protects underground water sources, including dug-wells, fro m contamination. This could be used for legal redress when the occupant of an adjacent plot locates his pit latrine at an unsafe distance from a dug well in his neighbour's plot.
Also, the Public Health Act Cap 242, Drainage & Latrine Rules (rules under Section 126) states that "No person shall construct or provide latrine accommodation of the kind known as pit closet or latrine accommodation situated over any hole or excavation in the ground which hole or excavation is intended for the reception of human excreta, except where, in the opinion of the local authority, the site of such proposed accommodation and the character of the soil are in every respect suitable and satisfactory for such a purpose, and the local authority has signified its approval in an Unplanned Peri-Urban Settlement: A Case Study of Langas -Eldoret M unicipality, Western Kenya thereof in writing, and then only subject to such conditions as the local authority may prescribe'' [10]. Local authorities thus have an important role in approving the distance between latrines and dug-wells in any area (including unplanned settlements such as Langas) under their jurisdiction. Under no circu mstances should any local authority neglect this important legal role.

Conclusions
In the Langas, an unplanned peri-urban settlement, where on the average, dug-wells are placed at less than 20 metres fro m pit latrines; there is an evidence of contamination of dug-wells due to latrine seepage. The fact that 98% of the sampled dug-wells in Langas had presence of coliforms implies that there was practically no chlorination being done.
The area dwellers did not follow adequate legal provisions in Kenya's public health and environmental laws which could have been used to abate the pollution of underground water. Similarly, the local authorities did not enforce the same laws and regulations.

Recommendations
In geographical areas with the same hydrogeological and geomorphological characteristics as Langas, we suggest that a min imu m distance of 38.5m between pit latrines and dug-wells could be adopted as a guideline. Th is is justifiab le given the fact that it is only the soil characteristics that directly determine whether or not latrine seepage will contribute to contamination of underground water in any given area.
In unplanned settlements such as Langas, the concerned local authority in collaboration with the M inistry of Water should strive to provide an adequately treated piped water supply. If they are unable to fulfil this obligation, they should provide free chlorine to residents for disinfection of dug-wells. Otherwise, if the chlorine is provided at a cost, it is likely that not many of the residents would be able to afford it . Alternatively, local authorities should install water-borne sanitation systems (sewerage) in such areas in which the main source of domestic water is dug-wells.
Routine health and hygiene education should be conducted in low-income communities because they are more predisposed to health problems as a result of prevalent unhygienic and unsanitary conditions. This education should be focused on proper hygiene behaviour, water d isinfection, well protection, etc. Both landlords and residents should also be sensitized that latrine seepage is a major source of dug-well contamination and therefore the recommended safe distances should be respected.
Our study did not investigate any association between the consumption of contaminated water fro m dug-wells and the prevalence of gastrointestinal diseases in the Langas area. Further studies should be done to evaluate the existence and impact of such a relat ionship.

Study Li mitations
This study had two limitations. First, hydrogeological and geomorphological characteristics of the Langas area were not established. Secondly, there was no control for the hygiene practices of dug-well users as a confounding factor contributing to contamination.

Ethical Considerations
Permission was sought and obtained from the Langas area government administrators, the Eldoret Municipal Council, owners of dug-wells and the Moi University School of Medicine Institutional Research and Ethics Co mmittee (IREC) before conducting the study.