To reduce operating pressures, it is sometimes necessary to introduce break-pressure tanks, which are usually made of concrete or ferrocement. If such tanks are used, the hydraulic gradient starts again at tank water level. If suitably sized, these tanks can be used within the system as storage tanks to meet peak demand.
Storage tanks are usually provided within the system to provide a total volume of storage equivalent to one day's consumption. The tanks may also be sited to either limit the maximum pressure in distribution pipelines or to sustain a pressure of at least 3 metres head at each tapstand whilst meeting the peak demands in the morning and evening(an entire day's worth of peak demand). Each tap should serve around 150 people.
Capacities of tanks should be 10 to 100 cubic metres, depending upon the size of the population to be served. Various materials have been used to construct them: masonry, reinforced concrete, concrete clockwork, ferrocement, galvanized mild steel, and GRP panels. In flat areas, tanks may have to be elevated on blockwork support structures. Tanks are roofed and, typically, are provided with a float controlled inlet valve, twin outlet pipes with stop valves, a scour pipe at low level for emptying and cleaning out, and an overflow pipe led far away from the tank.
The roof of the tank should have a sealed access manhole, and ventilators, covered in mesh fly screen, to allow air to be exhausted or admitted when raising or lowering the water level in the tank.
