Water Supply Industry Interpretations and Advice
- Area of Interest : Backflow prevention
- Topic : Fluid category
- Title : Back up supplies for grey water systems
- Clause Reference : Schedule 2 paragraph 15 (4)
- Reference Number : B43
- Decision Date : May 2010
As an alternative to installing a separate intermediate storage cistern an acceptable method for supplying back up mains water to a WC flushed using grey or rain water would be to install a cistern with two inlets arranged to form a type AB air gap as shown schematically in fig 1.