What are Rainwater Systems?

The term rainwater system refers to the equipment used and practice of capturing rainwater from a rooftop or the ground and storing it for future use. These systems often are called rainwater catchments and the use of one is often referred to as rainwater harvesting.

Rooftop rainwater systems are often used in developing nations to capture rainwater for use in irrigation or for watering livestock. In countries with public water systems, rainwater systems still are used to capture water for watering lawns. Rainwater often contains contaminates that make it unsuitable for human consumption.

Average rooftop rainwater systems capture rainwater running off a roof with eave guttering, downspouts, filtration catchments and a storage tank. Rainwater falls on the roof, runs into guttering attached at the eave and is channeled to downspouts. A filtering rainwater system then moves the water from the downspout into an underground catchment where it flows through a sand filter into a storage tank. This same process can be constructed with above-ground tanks as well.

Potable water rainwater system have special filtration equipment to make it safe for humans to drink. The water can be made potable by the addition of a pump to bring it from below ground into the house and through a more sophisticated filtration system. A reverse-osmosis filter is commonly used to make sand-filtered rainwater fit for human consumption.

Ground-level rainwater systems typically harvest rainwater through use of natural materials. These often are called hillside catchments because they are constructed using the slope of a hill to catch and filter the water. Rainwater runs down a hillside into a catchment pool that is damned up on its downhill side with close-packed rock and silt, which acts as a filter. The water is pulled by gravity through the natural filter and collected in either a naturally occurring depression in the land, often called a tank, or in a cistern.

In many countries, rainwater harvesting using rainwater systems is a necessity. Lack of public water systems combined with long dry seasons make collecting rainwater an important tool in farming or ranching. Such systems have long been in use in the more arid areas of China and Brazil.

In some regions of the United States the use of rainwater systems is closely regulated. Some states require newly constructed homes to have rainwater systems. Other states do not allow rainwater systems unless the homeowner also owns the water rights to the property. This law resulted from residents complaining that rainwater systems on homes keep rain from flowing into a particular area’s watershed areas.