Page 283 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 5 Cold water systems

Control of the system is automatic. The system contains a submersible or
surface-mounted pump to bring the water to the surface, filtration and
sterilisation equipment (usually UV), a pressure transducer to sense pressure
drop across the installation, a pressure gauge and an accumulator. The kitchen
sink is usually installed with water under pressure direct from the accumulator.
All other outlets are supplied from a low-pressure supply from a storage cistern
situated in the roof space. A non-return or check valve must be fitted upstream
of the accumulator.

Pumped supply with level control

This system uses a float switch to monitor the level of the water in a storage
cistern. The storage cistern is normally situated in the roof space of a dwelling.
The float switch operates a surface-mounted pump, which fills the tank until
the level of the float switch is reached. All water for the dwelling passes through
the storage cistern and this supplies all outlets with a low-pressure supply.
Water fed direct from the borehole to a kitchen sink under pressure is not
possible with this installation.

Storage cistern
Float switch controlling pump

Impervious strata
Sandstone aquifer

Surface-mounted pump Gate/isolator
valve Gravity feed
distribution
to all outlets

Filter

p Figure 5.33 A typical borehole installation with level control

Because all of the water for the dwelling is supplied at low pressure, this system
can also be used with supplies that are fed via a catchment tank in a stream
or spring via an external break/storage cistern. It is also possible to use water
direct from a catchment tank without the use of a pump, provided that the
source of water is higher than the dwelling. It must be remembered, however,
that some form of filtration and sterilisation of the water is necessary. A non-
return or check valve must be fitted upstream of the pump.

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