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.