Rainwater harvesting put simply means collecting and storing rain for future use. Uses depends on how far you go in purifying and cleaning the water, but could range from turning it into fully drinkable water to using it for cleaning and bathing to using it to water crops in a drought. The most common form of rainwater catchment system is a rooftop system, where runoff is directed into rainwater containers or tanks.

A close cousin of rainwater harvesting is called "groundwater recycling". These systems also recycle rainwater but usually in order to concentrate it in a single area, like where crops are to be grown. This is also referred to as "groundwater recycling" and is common where wells provide enough water for the people and animals, but are strained to meet the needs of crops or other vegetation. The term for changing groundwater into a drinkable form is called "groundwater recharging", and it is particularly common in areas that have rainy seasons.

Rainwater harvesting can provide water for human and animal consumption while at the same time reducing water bills, decreasing the costs of distribution, providing valuable reserves during times of drought, and saving some land that would otherwise have to be used for reservoirs. This can be vitally important in parts of the world where rain is scarce or the population is high, but in almost any area rainwater harvests can reduce costs and the strain on natural resources.

Rainwater harvests got their start in dessert or at least semi-arid locations. People in these areas often had limited, expensive, or strained access to regular sources of "potable" water. In these areas, rain harvesting provided drinking water, water for bathing and cleaning, water for livestock and pets, and of course irrigation and groundwater for crops and plants. The technology was developed and perfected out of need, but can now be more generally used. In fact, rainwater harvesting has now become more and more common in areas where the human population has outstripped natural resources.

Rainwater harvested from roofs can contain impurities picked up from the roof itself. In addition, some natural rain contains pesticides and other contaminants. Therefore, sometimes the water in rainwater tanks or containers has to be purified before it is to be used as drinking water, and this can be done through boiling, filtering, or through the use of additives like chlorine. Rainwater purification can also be done earlier in the process, quite simply by having filters in the tubing that directs the water into the storage tanks.

Rain collection systems are inexpensive, and can be built into structures so they are barely visible. Rainwater tanks or containers can be buried in the ground or located in a basement, again, invisible but highly useful. Rooftop systems can be made virtually invisible from ground level though sometimes they can be made to be aesthetically pleasing by choice. Look into rainwater harvests – it could save you money, help you reduce your impact on our environment, and bring you a stream of fresh water each day.