On-Site Sanitation and Its Effects on the Groundwater Resources of Nyali-Bamburi-Shanzu and Diani-Chale, Kenya

Abstract

This paper has analyzed the effects of on-site sanitation systems on groundwater and the impact this has to public health in the human settlements and tourist establishments of Nyali-Bamburi-Shanzu and Diani-Chale areas –two, very important tourist destinations in the Kenya coast. The pit latrine and septic-tank/soakage pit are the two main systems used for containing human waste in the settlements. These two on-site sanitation systems constitute the main source of potential contamination to groundwater and its consequences in the two areas. Hence, the boreholes and wells in the two study areas were located on a map using a GPS to serve as the sampling points. Water from these sources was analyzed for nutrient and feacal contamination in the laboratory. The nutrient contamination was established through the levels of total ammonia, nitrates/nitrites, and phosphates. These were determined using calorimetric methods; while the 5-tube, 3- dilution, Most Probable Number (MPN) technique was used for the evaluation of the levels of total Coliforms and Escherichia Coli (E-coli) parameters. The study was designed with a strategy that captured the effects and impacts of the contaminants with the varying tourist seasons and rainfall pattern. Results of the study revealed that the level of nutrient and micro-bacteria contamination varied with location, distance, tourist seasons and rainfall pattern relative to the contaminating sources. Water sources located within the human settlements and beach hotels –and within short distances to the contaminating sources exhibited elevated levels of nutrients and micro-bacteria; water sources located down-stream the human settlements revealed even higher contamination levels, indicating more input of nutrients and micro-bacteria probably through underground flow and seepage into the water aquifers –likely through cracks in the coral rock formation characteristic of the two study areas. The results of the study lead to the conclusion that on-site sanitation systems, though sanctioned for human waste disposal, may not be suitable in areas dominated by coral geology basement, particularly so when stringent observance of regulations and standard required in the construction of the waste disposal systems are not adhered to. Out of the conclusion, it is recommended that a shift towards innovative approaches in human waste management need to be advanced and pursued as a matter of policy in environmental management.

Keywords: On-site sanitation, water contamination, nutrients, micro-bacteria, Total coliform, E. coli