Efficiency Evaluation of Low-Cost Filtration Media for Rainwater Harvesting in Rural Households

Access to safe drinking water remains challenging for rural communities in northern Thailand where groundwater quality issues and infrastructure limitations restrict reliable supply options. This research evaluates the performance and economic viability of low-cost filtration systems using locally available materials for household-scale rainwater treatment, addressing the need for affordable point-of-use water treatment technologies suitable for resource-limited settings. Four filter configurations were systematically compared: sand-only, sand with gravel support, sand with activated charcoal, and a complete multi-layer system incorporating mesh screening, graded gravel, river sand, coconut shell activated charcoal, and support media. The experimental program was conducted at Chiang Mai Institute of Technology between May 2022 and April 2023, with field validation in three rural villages of Chiang Rai Province during the 2023 monsoon season. Water quality parameters including turbidity, total coliform, Escherichia coli, iron, and organic matter were monitored through 12 sampling events spanning wet and dry seasons. The complete multi-layer system achieved optimal performance with turbidity removal of 94.2%, total coliform reduction of 89.4%, and E. coli removal of 91.2%, meeting World Health Organization guidelines for drinking water quality. Construction costs totaled 850 Thai baht using materials sourced within 20 kilometers of installation sites, with operational costs averaging 31 baht monthly for media replacement and maintenance. Economic analysis demonstrated payback periods of 3.8 months compared to vendor-supplied water and 1.9 months compared to bottled water purchases typical in the study area. The findings establish that appropriately designed low-cost filtration systems can provide microbiologically safe drinking water from harvested rainwater at costs accessible to rural households earning minimum wage incomes, offering a sustainable complement to centralized water supply infrastructure development.