Rainwater Collection Sizing Calculator

Sizes rainwater harvesting systems based on roof area, rainfall, and demand.

Horizontal projection.
sq ft
Local climate data.
inches
Typical 75-90%.
%
Irrigation, flushing, etc.
gallons/day

Results

Annual Rainwater Yield-gallons
Percent of Annual Demand Met-%
Recommended Storage Volume-gallons
References: IPC Appendix C, ARCSA, Texas Water Development Board