Rainwater Harvesting in Kerala Soils
Technical instructions on designing catchment zones, filter structures, and recharge wells for tropical soils.
By Ar. Thomas John•Updated: 20/6/2026•1 min read
Kerala receives high rainfall during the monsoon season. Capturing this water prevents soil erosion and secures drinking water throughout the summer.
Catchment Area Design
- Roof catchment surfaces must be free of toxic paint coatings or lead flashings. We recommend clay tiles or high-grade food-safe polyurethane roof layers.
- Gutters must maintain a minimum slope of 1:100 to ensure self-cleaning velocity.
Filtration Stages
- First-Flush Diverter: Discards the first 10-15 minutes of rainfall which contains dirt and dry leaves.
- Slow-Sand Filter: The water passes through layers of fine sand, charcoal, and pebbles to remove microscopic particles.
- Storage Sump: Sized at 10,000 to 25,000 liters based on building size, built below-ground using reinforced RCC waterproof slabs.
Recharge Well Systems
In regions with low water tables, excess water is diverted into shallow recharge trenches to replenish local groundwater reservoirs without causing soil saturation.