Cisterns have been used as the entire water supply plan in diverse places such as Turkey, Mexico, certain cities in the Roman Empire, and multiple island nations. Basically, they are underground storage tanks that can range from modest to enormous and are sized according to the roof on site. Rainfall is funneled and directed into the cistern for storage until needed; this water can be used for irrigation or fire protection.
In an era of drought, a cistern is an incredible investment in the value of your home. Ultimately, it may be a bigger bang for your buck than installing a rain barrel or two. Tree People offers online information about how to get rain barrels and cisterns.