Storage of Water: Purpose and Capacities | Sanitary Engineering

In the buildings, the storage of water is required for the following purposes:

(i) For supplying the water to the consumers during non-supply hours,

(ii) For reducing the maximum rate of demand on the water mains,

(iii) For storage of watering during interruption to damage, repair etc. of the water mains,

(iv) When the available head is insufficient to supply the water in each Storey in multi-storey buildings.

The reservoirs, cisterns and storage tanks are generally constructed of cast iron, wrought iron or galvanized mild steel plates. Sometimes R.C.C. storage tanks are also used. These tanks may be circular, square or rectangular in plan. The storage tanks may be kept on the roof of the building or on the ground. The storage tanks should be water-tight and provided with an efficient mosquito proof wanting pipe.

The outlet of this warning pipe should be placed in such a position so that the discharge of the water can be readily seen. One overflow pipe is also provided in the storage tank. Ball valve should be provided in the tank to control the flow of water in the tank. All the storage tank should be provided with a scour or drain pipe near the bottom to clean the tank. The storage tanks are provided with outlet pipes to draw the water.

The quantity of water to be stored depends on the following factors:

(i) Rate supply water from water works,

(ii) Type of buildings such as residential, public or industrial,

(iii) Whether water supply is continuous or intermittent, and

(iv) Frequency of replenishment of overhead tanks, during the 24 hours,

Indian Standard Institution has recommended a minimum of 135 litres/head/day in residential buildings having full flushing system.

Table 24.1 and 24.2 give the storage capacities as per I.S. 2065-1963.

Notes:

1. If the premises is situated at a place higher than the road level in front of the premises, storage at ground level should be provided on the same lines as on first floor.

2. The above storage may be permitted to be installed provided that the total domestic storage calculated on the above basis is not less than the storage calculated on the number of down-take as per scale given below:

(a) Downtake pipe – 70 litres each.

(b) Showers – 135 litres each.

(c) Bath tubs – 200 litres each.