Last updated: February 2024

RPZ FAQs: General

What is an RPZ valve?

Also known as a BA device, an RPZ valve is mechanical backflow prevention device capable of providing protection, against both back pressure and back siphonage, up to and including fluid category 4.

By means of a combination of check and relief valves an RPZ valve aims to ensure the water downstream is at a lower pressure than the incoming supply.

The installation, including relocation, of RPZ valves must be notified to the local water

undertaker. RPZ valves must be installed and tested in accordance with the Water Industry Approved Installation Method (AIM 08-01).


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Uncontrolled if downloaded. This is informative, non-statutory guidance and intended for general guidance purposes only; it is subject to change.

Compliance with this information should not be relied upon as guaranteeing no enforcement action will be taken by water undertakers. Water Regs UK accepts no liability for loss, indirect or consequential loss arising from or in connection with this guidance document.

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