Submerged ground rainwater tanks
Submerged ground rainwater tanks may also be used for retention of storm-water (water from roof and paved areas) for release at a later time, though this is not suitable for use in the home. Conventional rain water ranks are not designed simply to put underground and backfilled with soil. These will collapse and may pop out of the ground if empty. Special underground tanks are built, but are very expensive otherwise a special room may be built with a concrete floor and roof with brick walls, all of which possibly make underground tanks unviable, but if this is the only source of water this may be necessary.