A study of the bacteriological quality of roof-harvested rainwater and an evaluation of SODIS as a suitable treatment technology in rural Sub-Saharan Africa

Harvested rainwater (HRW) is of great socio-economic importance particularly in areas where water sources are scarce or polluted. This case study was carried out in a rural area of Southern Uganda where the community has limited access to safe drinking water. The aims of the project were to investigate the quality of harvested rainwater over a year long period covering wet and dry seasons and to investigate the use of solar waterdisinfection (SODIS) as a water treatment technology. Fifty households using roof HRW were selected. The systems used included catchment ponds, metallic, concrete and plastic tanks. All households used the HRW for drinking. The raw HRW was analysed for temperature, pH and total dissolved solids (TDS) and for the presence of the bacterial indicators of faecal pollution – Escherichia coli, faecal enterococci and Clostridium perfringens. Results indicated that while the HRW met the required physiochemical drinking water standards, the majority of samples from all types of system showed levels of microbiological contamination indicating that the water was unsafe for drinking without treatment. The use of SODIS to treat the water was investigated using 2 Liter PET bottles and was shown to be an effective treatment technology.