A Longitudinal Study of Long-Term Change in Contamination Hazards and Shallow Well Quality in Two Neighbourhoods of Kisumu, Kenya

Abstract

Sub-Saharan Africa is experiencing rapid urbanisation and many urban residents use groundwater where piped supplies are intermittent or unavailable. This study aimed to investigate long-term changes in groundwater contamination hazards and hand-dug well water quality in two informal settlements in Kisumu city, Kenya. Buildings, pit latrines, and wells were mapped in 1999 and 2013–2014. Sanitary risk inspection and water quality testing were conducted at 51 hand-dug wells in 2002 to 2004 and 2014. Pit latrine density increased between 1999 and 2014, whilst sanitary risk scores for wells increased between 2002 to 2004 and 2014 (n = 37, Z = −1.98, p = 0.048). Nitrate levels dropped from 2004 to 2014 (n = 14, Z = −3.296, p = 0.001), but multivariate analysis suggested high rainfall in 2004 could account for this. Thermotolerant coliform counts dropped between 2004 and 2014, with this reduction significant in one settlement. Hand-dug wells had thus remained an important source of domestic water between 1999 and 2014, but contamination risks increased over this period. Water quality trends were complex, but nitrate levels were related to both sanitary risks and rainfall. Given widespread groundwater use by the urban poor in sub-Saharan Africa, the study protocol could be further refined to monitor contamination in hand-dug wells in similar settings.

An Assessment of Inter-Observer Agreement in Water Source Classification and Sanitary Risk Observations

“…We graphically compared the distance to nearest latrine estimated by Observer A against those estimated by the remaining five observers, calculating Lin's concordance correlation coefficient and related statistics (Bradley and Blackwood 1989) for these estimates using the Stata version 15.0 concord and batplot utilities. For each source and observer, we calculated a percentage sanitary risk score as the number of hazards present as a proportion of those observed, following common practice in analysing such data (Howard et al 2003;Misati et al 2017;Okotto-Okotto et al 2015). We again computed Bland and Altman limits of agreement and related statistics for Observer A's records against those of each of the remaining five observers.…”

“…Six observers participated in this exercise and were deliberately chosen to have varying levels of prior experience and education. The 'gold standard' observer (Joseph Okotto-Okotto, JOO; Observer A) had over 20 years' experience of sanitary risk observation, publishing several papers on this topic (Okotto-Okotto et al 2015;Wright et al 2013) and managing multiple rural water supply projects. A second (Observer E) also had previous experience of sanitary risk observation and some tertiary education and together with two recent graduates (Observers B and F) were recruited to typify survey team members who might support a regional or national water point mapping exercise.…”

Identification of Human and Animal Fecal Contamination in Drinking Water Sources in the Kathmandu Valley, Nepal, Using Host-Associated Bacteroidales Quantitative PCR Assays

“…Their construction and well depths might make shallow dug wells and stone spouts more vulnerable to contamination compared to both types of tube wells. Deep tube wells are expensive to construct; therefore, inexpensive shallow wells are widely used, which results in large populations being vulnerable to potential hazards [13].…”

“…Urbanization and agriculture can also substantially degrade water quality, causing eutrophication and fecal contamination [11,12]. The primary source of the fecal pollution of water sources may be the improper management of human waste, which is often coupled with leakage in sewer pipes, the improper construction of septic tanks, and the use of pit latrines, all of which dispose of human waste in the subsurface [13]. In some agricultural areas in Cambodia, animals have been found to be primary sources of the fecal pollution of water sources [3] and significant association of livestock ownership with drinking water contamination in Ghana and Bangladesh has been reported [14].…”

Bacteriological quality of drinking water in the Atebubu-Amantin District of the Brong-Ahafo Region of Ghana

“…In many African communities, hand-dug wells have become a major means of obtaining domestic water (Cronin et al 2007). Hand-dug wells are relatively cheap to construct and maintain (Water Aid 2013) but they are often at risk of contamination due to a number of factors, including inflow from surface runoff, contamination as water is abstracted by users, and/or contaminant transport through the unsaturated and saturated zones (Okotto-Okotto et al 2015). It is estimated that in the developing world, 80 % of all diseases are directly related to poor drinking water and insanitary conditions (UNESCO 2006).…”