Impacts of Pit latrines on Groundwater Quality in Squatter Settlements in Zanzibar

Groundwater is the major source of drinking water in Zanzibar. Most of the people in squatter settlement rely on shallow groundwater due to insufficient supply of treated water. In these areas, shallow wells are located close to pit latrines, the condition which increasing the risk of contamination. This study aimed to assess the impact of pit latrines on groundwater quality in five sub-urban areas of squatter settlements in Unguja Island. Water samples were collected from twenty shallow wells and analyzed for the microbiological and physio-chemical parameters. The Ordinary Least Square (OLS) regression model was used to assess the influence of distance from pit latrine to the groundwater sources. The data revealed that nitrate and chloride concentrations increases when the distance between the shallow wells and the nearest pit latrine decreases. In contrary, faecal coliform counts shows that for every unit increase in the distance from pit latrine to the shallow wells the counts decreased by 42 CFU/100 ml. However, OLS regression model did not show significant relationship of total coliform and distance from the well. This study suggests that there are other factors that may accelerate the total coliform bacteria in water wells. These results illustrate that public health risks associated with waterborne diseases could be ranked high at densely populated squatter settlement. Thus, the study recommends that routine monitoring of shallow wells is required as well as application of low-cost technologies such as raised and lined pit latrines in order to minimize potential risk of groundwater pollution.