Rain water harvesting can be done simply with a barrel and a hose, or it can involve a larger, more elaborate system that stores water in an underground tank for everyday use in the home. In areas where water is of high value, catching rain water is one of only a few options for obtaining usable water, so larger, more elaborate rain water harvesting systems may be used. Gardeners, however, may use a simple barrel and hose system that gives them more water to use on the garden or lawn.
A ground catchment system is used in areas where water is scarce. It is a difficult method to set up correctly, though if it is done correctly, it can catch a significant amount of water. The system works by collecting rain water and runoff from higher elevations. The water is set to flow through a filtering system, usually consisting of rocks, sand, and other filtering materials; it is then allowed to flow into a basin for storage. The water can then be funneled into homes or wells for use. It is one of the rarer forms of rain water harvesting, and it is not common in areas that get regular rainfall.
A rain harvesting system that is more common on individual homes is the rooftop collecting system. A concrete catchment is built on the roof of a home, and a series of gutters and pipes moves water down to a tank on the ground level. The water is then filtered and stored in a clean underground tank. It is pumped into the home through yet another filter before use inside the home. Such rain water harvesting systems can be expensive to set up, and they require regular cleaning and maintenance to prevent disease and contamination from insects and animals.
Simpler rain water harvesting systems for the lawn or garden require a small investment of time and money to set up, and they can be used for watering lawns or gardens, or for other purposes around the yard. The most common rain water harvesting system for such purposes is simply a large plastic or metal barrel with a filter on top. Rain water can be collected in the barrel, which has a spigot on the bottom so a garden hose can be attached to it. If the barrel is placed under a gutter or a rain water drip chain, it will collect even more water more quickly. Water collected in such a system should not be used as drinking water unless it is properly sterilized.