Physicochemical and Microbiological Water Quality, Contamination Pathways, and First Flush Treatment Efficiency in Household Rooftop Rainwater Harvesting Systems in Kagera Region, Tanzania

Abstract

The objective of this paper was to assess the Physicochemical and Microbiological Water Quality, Contamination Pathways, and First-Flush Treatment Efficiency in Household Rooftop Rainwater Harvesting Systems in Kagera Region, Tanzania using questionnaires, interviews, observations in the field, lab analysis, and experimentation method. Samples of water from 30 household roof rainwater harvesting systems were taken and analyzed using SPSS version 29 and thematic analysis. Poor maintenance, dirty gutters, corroded roof sheets, bird droppings, open water tanks, and poor sanitation were found to be the major contamination routes. The harvested rainwater had the following average values: pH (5.70 ± 0.41), turbidity (4.17 ± 1.32 NTU), electrical conductivity (85.67 ± 12.45 µS/cm), total dissolved solids (43.17 ± 10.26 mg/L), and total coliforms (2.80 ± 1.12 CFU/100 mL). Most physiochemical characteristics met the required standards set by WHO and Tanzania on potable water. However, total coliform bacteria were found to be above the recommended threshold of 0 CFU/100 mL in some samples. From experimentally determined data, it was observed that the use of first-flush diverters lowered the turbidity in the collected rainwater by 82.07±4.61%. It was concluded that the quality of collected rainwater is highly dependent on maintenance and contaminant removal procedures. Maintenance of the rooftop collection systems, pre-treatment of collected rainwater before consumption, and the use of first-flush diverters were suggested.