Collect Rainwater from Roof

Estimate roof runoff wey you fit collect from one rainfall event.

Your numbers

Water wey collection fit produce

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Estimate water wey you fit collect from one rainfall event, using collection efficiency and space wey remain inside tank wey you enter. E no forecast rain or assess water quality and drinking safety.

Formula

Use V = Are. A na roof catchment area for m², r na rainfall for mm, and e na collection efficiency as fraction. V na potential collected litres; actual storage no fit pass di spare tank capacity wey you enter.

Estimate roof runoff wey you fit collect from one rainfall event.

Example wey show the calculation

Roof area wey collect rain (m²): 100
Depth of rainfall (mm): 20
Efficiency of rainwater collection (%): 80
Free space inside tank (L): 1000

Water wey collection fit produce: 1,600 L
Water stored with free space wey you enter: 1,000 L
Water wey overflow: 600 L

Where e fit work and limits

Estimate water wey you fit collect from one rainfall event, using collection efficiency and space wey remain inside tank wey you enter. E no forecast rain or assess water quality and drinking safety.

We check inputs for missing values and allowed ranges. Result wey pass the finite numeric range no go show. Rounding affect wetin display, while calculation use the model numeric precision.

Check your units and assumptions before you rely on result. Changing label no convert currency or physical unit.

Version of di formula: 109454605e61 · Example don get check: 2026-10-30

Method