Also called rain catching, these simple systems connect downspouts (gutters) to a central water tank capable of holding about 100,000 litres of water or more. Often, in African countries, the issue is not that it never rains, but rather that when it does, most of the runoff is lost. These water systems make the best use of what little rain there is.
Rain water harvesting has been around for hundreds of years. It is in use in developed and under-developed nations alike. In Australia for instance, many homes away from the cities use it as a primary source of water.
These simple systems are cost-effective and last for a long time. In communities that have medical clinics, schools and other larger-roofed structures they do a great job of collecting much needed water to use throughout the year.
In some communities the tanks have been filled with municipal sources that are often very unreliable and thus available only parts of the year. By filling the tanks at such times, in addition to collecting rain water, the community was able to end their harsh “dry season” rationing of water to school children.