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☔ Rainfall Harvesting Calculator

Calculate annual water that can be harvested from roof or catchment area.

Catchment Area (m²)Roof or catchment area

Annual Rainfall (mm)Average yearly rainfall

Capture Efficiency (%)System collection efficiency

📐 How It Works

Harvested Water = Area × (Rainfall ÷ 1000) × (Efficiency ÷ 100) × 1000