Rainwater harvesting calculator
Estimate an illustrative collection volume from rainfall, catchment area and a stated runoff coefficient.
RESULT
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m³
Enter your values and calculate
The formula
Volume (m³) = rainfall (mm) × area (m²) × coefficient / 1,000.
Choose a coefficient appropriate to your surface and purpose. First-flush diversion, storage capacity, water quality and operational losses need separate assessment. The example is not a local rainfall forecast.
Follow the method
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