Impact of Seasonal Variation on the Microbiological and Physicochemical Quality of Stored Rainwater in Underground Tanks

Rainwater harvesting (RWH) is an essential water resource, particularly in regions experiencing water scarcity. However, the quality of stored rainwater varies due to environmental contamination and seasonal changes, affecting its suitability for domestic and agricultural use. This study examines the impact of seasonal variation on the microbiological and physicochemical quality of stored rainwater in underground tanks in Ogbadibo Local Government Area, Benue State, Nigeria. A total of 234 water samples were collected from 27 underground tanks across three different seasons. The study assessed key physicochemical parameters such as pH, turbidity, total dissolved solids (TDS), hardness, and heavy metal content, alongside microbiological indicators including total viable count (TVC) and total coliform count (TCC). The results revealed significant seasonal fluctuations in water quality. During the rainy season, higher turbidity and microbial loads were observed due to increased surface runoff contamination, whereas the dry season exhibited elevated heavy metal concentrations due to prolonged water storage and sedimentation. Microbial contamination exceeded WHO permissible limits, with coliform levels peaking in the wet season. Statistical analysis using ANOVA and Duncan Multiple Range Test (DMRT) confirmed the seasonal impact on physicochemical and microbiological parameters. While aluminum sulfate (alum) demonstrated effective microbial reduction, plant-based biotreatment methods, such as banana peels, orange peels, almond leaves, and Moringa oleifera seeds, emerged as promising eco-friendly alternatives for improving stored rainwater quality. The study concludes that seasonal variations significantly influence the microbiological and physicochemical quality  of stored rainwater, posing potential health risks. It recommends regular water quality monitoring, optimization of plant- based biotreatment techniques, and increased public awareness on sustainable water treatment practices. These findings  contribute to advancing low-cost, environmentally sustainable solutions for enhancing rainwater safety in resource-limited communities.