Size the barrels for one downspout and a typical storm. It also shows how little rain fills a single barrel, which surprises most people.
How it works
Roof area × inches of rain × 0.623 gallons × the share captured gives storm gallons. Divide by barrel size and round up.
Before you order
- Connect barrels in series near the top so they fill evenly.
- Screen every opening to keep mosquitoes out.
- Drain barrels before a hard freeze so they do not split.
Common questions
How fast does a rain barrel fill?
Quickly. A 500 sq ft roof section can fill a 55 gallon barrel with less than a quarter inch of rain.
How much does a full rain barrel weigh?
A 55 gallon barrel weighs about 460 lb when full, so it needs a solid, level base.