Open consultation

Consultation on the proposed revisions to the Approved Installation Method AIM 08-01 for Type BA Device – Verifiable Backflow Preventer with Reduced Pressure Zone (RPZ Valve)

This consultation runs from Thursday 1 February 2024 to Wednesday 1 May 2024.


The Water Supply (Water Fittings) Regulations/byelaws in England, Wales and Northern Ireland, byelaws in Scotland are legal requirements which apply to all premises which have, or will have, a mains water supply. They are an important item of public health legislation, their purpose to safeguard drinking water supplies both on site and the in the wider drinking water supply network.

This consultation provides the opportunity to review and comment on proposed revisions to Water Undertakers’ Approved Installation Method (AIM 08-01) – Type BA Device – Verifiable Backflow Preventer with Reduced Pressure Zone (RPZ Valve) (hereafter referred to as the RPZ AIM) approved by the water undertakers listed.


The proposed changes are in response to concerns about the suitability and accuracy of some test equipment. The changes have taken consideration of good practice adopted in countries with a longer history of RPZ valve use and testing. It also highlights the need for testers to have a better understanding of test equipment calibration processes and certification.

Changes made included:

  • A new layout making it easier to navigate and understand the requirements of the AIM.
  • A description of the minimum specification for RPZ test equipment and clarification of the need to interpret calibration certification.
  • The periodic revalidation of testers knowledge to ensure competency is maintained.

Your views

We are interested in your views on the following:

  1. Does this updated version of the RPZ AIM make clear the requirements and responsibilities of designers, installers, testers, as well as those of customers and businesses, for the installation and ongoing testing of RPZ valves in order to comply with their statutory obligations?

  2. To what extent do you agree or disagree there is sufficient time for transition to meet the requirements of this updated version of the RPZ AIM. Please give your reasons.

  3. Do you have any other comments on the updated version of the RPZ AIM?

How to respond

You are welcome to comment on any aspect of this proposed revision.

View the draft Approved Installation Method document (click to open or download)

Use the Consultation Reply Form to register comments (click to download a copy of the Reply Form)

You can:

  • Respond by email, by completing electronically the consultation reply form and returning it to This is the preferred method.


  • Respond on paper – you can do this either by:
  • Printing the consultation reply form; or
  • Making a written response in whatever format you wish.

Post your completed response to:

The 2024 RPZ AIM consultation
Water Regs UK Ltd
Unit 13 Willow Road
Pen Y Fan Industrial Estate
NP11 4EG

All responses must be received by 17:00 pm Wednesday 1st May 2024

How your responses will be handled

Representatives of Water Regs UK subscribers will give full consideration to the substance of arguments in the responses received and make recommendations to water undertakers.

Queries and complaints

If you have any queries in this document or the consultation on these proposals, or if you are not satisfied with the way this consultation exercise has been conducted, please write to Water Regs UK care of the above address.

Next steps

Following consultation a final draft of the RPZ AIM will be approved by water undertakers before notifying Regulators’ in accordance with the requirements set out in:

  • Regulation 12 (3) of The Water Supply (Water Fittings) Regulations 1999
  • Regulation 11(1) of The Water Supply (Water Fittings) Regulations (Northern Ireland) 2009
  • Byelaw 4(6)(a) of The Water Supply (Water Fittings) Byelaws (Scotland) 2014.

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