Covered cisterns and the water in them are defined as an integral part of an insurable building, meaning under the building or above ground and physically attached to a side of the building with one of the walls of the building and cistern being common to each other
A cistern is a container for storing rain water. a container in which the supply of water for a building is stored inside the building = tank (cisterne, from cisterna, from cista )
an underground tank or pipe to collect storm water runoff from catch basins prior to discharge into sewer systems Cisterns are used to store and slowly release storm water from residential areas into the combined sewer system until the threat of CSOs has passed