Water Supply in Public Buildings

14. Design of plumbing systems

for multi-storey buildings

14. DESIGN OF PLUMBING SYSTEMS FOR MULTI -STOREY BUILDINGS

For plumbing purposes, the term “multi-storey” is applied to buildings that are

too tall to be supplied throughout by the normal pressure in the public water

mains. These buildings have particular needs in the design of their sanitary

drainage and venting systems. Water main supply pressures of 8–12 metres (25–

40 feet) can supply a typical two-storey building, but higher buildings may need

pressure booster systems. In hilly areas, the drinking-water supply pressures

will vary depending on the ground elevation. In these cases, the water authority

may have to specify areas where particular supply pressures can be relied upon

for the design and operation of buildings. Where a building of three or more

storeys is proposed a certificate should be obtained from the drinking-water

supply authority guaranteeing that the present and future public drinking-water

supply pressure will be adequate to serve the building. If the public water

pressure is inadequate, suitable means shall be provided within the building to

boost the water pressure.

14.1 Systems for boosting water pressure

Pressure-boosting systems can be of several different types:

• pumping from a ground level or basement gravity tank to a gravity roof

tank;

• pumping from a gravity storage tank or public water main into a hydropneumatic pressure tank that uses captive air pressure to provide adequate

drinking-water supply pressure;

• installation of booster pump sets consisting of multiple staged pumps or

variable speed pumps that draw water directly from a gravity storage tank

or the public water main. Multistage booster pump sets typically include

discharge pressure regulating valves to maintain a constant drinking-water

supply pressure.

Written approval should be obtained from the appropriate authority before any

pump or booster is connected to the...