A
rainwater tank (sometimes called a
rain barrel in North America in reference to smaller tanks, or a
water butt in the UK) is a
water tank used to collect and store rain water
runoff, typically from
rooftops via
rain gutters. A rainwater catchment or collection (also known as "
rainwater harvesting") system can yield 2358 litres (623 gal) of water from 2.54 cm (1 in) of rain on a 93 m
2 (1,000 sq ft) roof. Rainwater tanks are devices for collecting and maintaining
harvested rain.