Mitigating the effects of septic tank effluents from households on groundwater quality: a case of Meanwood-Kwamwena, Lusaka

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Daka, Francis Dabwiso
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University of Zambia
Disposal of household effluent by septic tank systems is the most common method carried out by people that live in Lusaka’s forthcoming settlements, in Zambia. Furthermore, water for domestic use is primarily supplied from private boreholes because of the absence of piped water; and lack of sewerage systems in the area is also an issue of concern to this problem. The Research was descriptive in nature and used mixed methods (quantitative and qualitative) for data collection. Then field observations were done in Meanwood-Kwamwena area followed by structured interviews with key stakeholders who were selected purposely based on their knowledge about septic tanks. The sample size for the study was 13 respondents. This was based on the consideration of a worst case scenario of 50 percent of households not complying with standards for mitigating groundwater contamination and 95 percent confidence level with 5 percent margin of error and a confidence interval of 27 percent. The sample size was determined using a website based sample size calculator from the website of The Survey System. Questionnaires and Personal interviews were used in this study. Also used was the 50m Tape measure and dip stick for measuring depth of the septic tank.GIS data was also obtained by GPS map 60 instrument. A sample size of 13 was drawn from the total population of 7100 that the researcher used for the purpose of the study which represented the total population. These were sampled randomly. In the study area, 38.5 percent of boreholes were found to be contaminated with feacal coliforms and total coliforms and most of these were at a lower elevation. Distances between borehole and septic tanks were limited by plot sizes and averaged about 50 percent less than the minimum required distance by WHO. A set baseline here was one where pollutants were within WHO standards. The findings also provided a basis for the selection of specific mitigation measures which would be cost effective. Contamination of groundwater quality calls for rigorous management measures to be put in place by relevant Government authorities to safeguard human health and the environment. Keywords: septic tank, effluent, contamination, groundwater quality, pollutants.
Septic tanks , Groundwater--Quality--Zambia , Groundwater pollution--Lusaka, Zambia