How we worked it out
Updated as you change the numbers.
- Gallons = footprint (sq ft) × rain (in) × 0.623 × efficiency. 1 cu ft = 7.48 gal and 1 in = 1/12 ft, so 7.48 ÷ 12 = 0.623.
Method and assumptions
Some states and cities regulate rainwater collection; check local rules. Rainwater from roofs isn’t safe to drink without treatment.
Questions
How much rain does a 600 sq ft roof collect from 1 in of rain?
About 318 gallons at 85% efficiency: six 55 gallon barrels.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.