Page 259 - 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

High-level grey water
storage cistern

Grey water
supply

Grey water feed
Grey water collection to cistern in the
roof space
Grey water
filter

Underground
storage cistern

Submersible
pump

p Figure 5.6 Grey water system feeding a WC

Rainwater harvesting
Rainwater harvesting has the potential to save a large volume of mains water
and reduce pressure on resources because water that would otherwise be lost
can be used to flush toilets, water gardens and feed washing machines, instead
of using water direct from the mains supply for such purposes.

Rainwater harvesters can be installed at domestic or commercial sites, and
average households can expect to save up to 50 per cent of their water
consumption by installing a rainwater harvesting system.

Harvesters are usually installed beneath the ground in an underground storage
cistern or on the roof of a flat-roofed building. A typical four-bedroom house
will capture enough water to keep a 5000-litre cistern in use throughout most
of the year.

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