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Sqratch Tools / MEP Systems / Rainwater Harvesting

Rainwater Harvesting

Calculate the potential volume of rainwater that can be harvested from a roof or paved area. Enter your catchment area, annual rainfall, and select the surface type to estimate the harvestable volume in liters and gallons.

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Basis & Assumptions

  • Harvested Volume (L) = Catchment Area × Annual Rainfall × Runoff Coefficient
  • Runoff coefficients dictate the percentage of water that makes it to the drain vs being absorbed/evaporated.

For quick design checks and study — not a substitute for your local Development Control Regulations, NBC provisions, or a licensed professional's judgement. Always verify against the bye-laws that apply to your site.