Extensive rainwater harvesting apparatus existed 4,000 years ago in the Negev Desert. In ancient Rome, residences were built with individual cisterns and paved courtyards to capture rainwater to augment water from the city's aqueducts. And as recently as early in this century, rainwater was the primary water source on many ranches, with stone and steel cisterns still standing today on homesteads. One of the beauties of rainwater harvesting systems is their flexibility. A simple system is a 55 gallon drum placed under a rain gutter downspout.
Rainwater offers advantages in water quality for both irrigation and domestic use.
Rainwater is naturally soft, contains almost no dissolved mineral or salts, and is free of chemical treatment. The shape of a water harvesting system depends upon the topography of the site, the type of catchment treatment, the intended use, and the personal preference of the designer. Microcatchments, strip harvesting, roaded catchments, and harvesting aprons are some the more common types used. The microcatchment procedure can be used in complex terrain or on steep slopes, where other water harvesting techniques may be difficult to install. The village of Shungopovi on the Hopi Reservation in northeastern Arizona is a good example of the use of water harvesting in dry regions.