Every property to be protected by a fire protection system needs sufficient water which should be available at all times to fight the fire.  The static storage is provided at the ground level and terrace level of the building by means of water storage tanks. The storage is provided generally in such a way that the municipal water supply is first received in the fire static storage tank from where it overflows to the domestic tank.  This holds good for overhead storage too.  Thus water will always be available in the event of a fire.  The capacity of the underground storage is generally based on at least half an hour's stock of water at the rated draw-off by the fire pump.

This tank also serves the purpose of a holding capacity into which water from tankers can be poured through an arrangement of a fire brigade breaching.