Cisterns
Cisterns are large rainwater storage tanks. They are made out of any impervious, water-retaining material and are only distinguishable from rain barrels because they are larger and have a different shape.
Located either above or below ground a cistern consists of a solid secure cover, a leaf / mosquito screen at the entrance, a coarse inlet filter with clean-out valve, overflow pipe, and a man hole, sump and drain to facilitate cleaning.