Water Supply Industry Interpretations and Advice

  • Area of Interest : Enforcement
  • Topic : Backflow prevention
  • Title : Type AUK1 air gaps
  • Clause Reference : Regulation 4 & Schedule 2 paragraph 15
  • Reference Number : E05
  • Decision Date : March 2014

The definition of an AUK1 air gap is given in section 6.3 of the Defra Guidance to regulations:

'Type AUK1 – Air gap with interposed cistern' means a non-mechanical backflow prevention arrangement consisting of a cistern with a Type AG overflow and an air gap; the spill-over level of the receiving vessel (WC pan or other receptacle) being located not less than 300 millimetres below the overflow pipe and not less than 15 millimetres below the lowest level of the interposed cistern.'

In addition to satisfying this requirement a Type AUK1 air gap must also comply with the requirements of regulation/byelaw 4(2). That is to say a Type AUK1 air gap must conform to an appropriate performance specification or standard.

In the absence of any other performance specification the only route by which to demonstrate compliance with both these requirements is conformity with Regulators’ Specification test code sheet 2213.14 plus acceptable evidence that the arrangement incorporates a Type AG air gap, please refer to interpretation E04

[Also see interpretation E03 & B58]