Main tool

Rainwater Potential Calculator

Enter your roof dimensions and local rainfall to estimate how much water you could harvest.

Inputs

Q = A × R × C, where A = area (m²), R = rainfall (m), C = runoff coefficient. 1 m³ = 1,000 L.

Estimated harvest potential

0 L/year

Catchment area

200 m²

Annual rainfall

700 mm

Monthly average

9,333 L

Storage range

14,500–29,000 L

Estimate of potential only — actual recovery depends on losses, overflow, maintenance and rainfall intensity.

61%

of demand

Share of a 500 L/day demand the potential could cover over a year.

Monthly harvest estimate (L)

Monthly split uses a typical monsoon distribution; enter monthly values for accuracy.

Water-saving impact

≈ 11,200 buckets (10 L) or 7 water tankers (15,000 L) per year.