Rain tanks and cisterns are containers that can capture rainwater runoff from rooftops and store that water for use at a later time. The stored water is then used to supplement or replace irrigation systems, providing water for plants, trees, and edible gardens. In the event of a major rainpour, these tanks may overflow. In this case, overflow from containers is slowed which provides more opportunity for water to sink into soil and into the groundwater table before running off a property and into the gutters. Tanks and cisterns provide greater storage space than rain barrels, and multiple tanks can be connected to increase total capacity.