Schedule 2 paragraph 15 of the water fittings regulations in England, Wales and Northern Ireland, byelaws in Scotland require every plumbing system to incorporate protection against backflow. This is often referred to as point of use backflow protection. It can be provided by an air or tap gap arrangement or a mechanical backflow prevention device.
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.
It comprises of a combination of check and relief valves in different zones which perform specific functions to ensure there is no backflow should the downstream pressure become higher than the incoming supply or the valve malfunctions.
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 RPZ Approved Installation Method (AIM ).
Please note: testing intervals will be at the discretion of the local water undertaker but not less than annually.
Two of the ways, there may be others, to find a competent RPZ tester include searching the lists of those approved contractor schemes which have an RPZ tester sector, or the WaterSafe website www.watersafe.org.uk.
To locate a RPZ tester using the WaterSafe website search, select ‘RPZ valves testers’ from the service option and enter the postcode for the premises where the valve is located. The results generated will listed by distance from this location.
If there is an RPZ valve installed at a premises you are responsible for, the things you need to do include:
Familiarise yourself with the RPZ AIM
Make sure the local water undertaker has been notified the valve exists and has granted consent and familiarise yourself with the conditions of consent
Confirm the valve has been installed and tested in accordance with the AIM and the conditions of consent issued by the local water undertaker
Ensure the valve is ‘in test’ – it has been tested within the timeframe specified in the condition of consent, by a competent tester using equipment which meets the required minimum specification and satisfies all the appropriate clauses of the RPZ AIM.
Make certain a copy of the test report has been sent to the local water undertaker within the required timescales
As part of your maintenance procedures consider maintaining a technical file
Notify the local water undertaker if you plan on any alterations to the plumbing on site including removing, relocating or replacing the RPZ valve
An information leaflet highlighting things those responsible for plumbing systems should be aware of if thinking about installing or already have RPZ valves installed can be found here.
RPZ valves, or BA devices, are a recognised form of backflow prevention offering protection against back pressure and back siphonage up to and including fluid category 4.
If a plumbing system in your premises has been categorised as fluid category 4 or less by your water undertaker, then an RPZ valve may be an appropriate form of point of use backflow protection. An information leaflet highlighting things those responsible for plumbing systems should be aware of if thinking about installing or already have RPZ valves installed can be found here.
An RPZ valve may also be suitable for wholesite backflow protection. For further information consult the local water undertaker.
Please note:
Only RPZ valves installed and tested in accordance with the RPZ AIM will be considered as providing backflow protection.
To show they are functioning satisfactorily all RPZ valves are required to be regularly tested by a competent RPZ tester. Test intervals are set by the local water undertaker. Whilst test intervals may vary, they will be at least annually.
Potential users of RPZ valves must be aware that water undertaker’s consent will always be conditional upon installation, commissioning and compliance testing requirements.
If you are thinking about an RPZ valve installed at premises you are responsible for, things you need to do include:
Speaking with the local water undertakers to find out whether you need an RPZ valve and if so where, and the valve, you are planning to install is suitable
Notify the local water undertaker
Familiarise yourself with the RPZ AIM,
Consider whether an RPZ valve is right for you – consent to install will always be conditional on ongoing testing requirements.
An information leaflet highlighting things those responsible for plumbing systems should be aware of if thinking about installing or already have RPZ valves installed can be found here.
In addition to manufacturers installation instructions RPZ valves must be installed and tested in accordance with the RPZ AIM
There are no legal restrictions on who can install an RPZ valve. But anyone undertaking this work should be competent to do so. Water undertakers recommend using an approved contractor.
Once installed an RPZ valve needs to be commission and compliance tested before it can be brought into service.
The valve will also need to be compliance tested, in accordance with the conditions of consent, at regular intervals thereafter, as well as following relocation or repair.
To comply with the RPZ AIM commission and compliance testing should only be carried out by someone competent to do so. Details of what water undertakers will consider as evidence of competency to test an RPZ valve are provided in the RPZ AIM glossary.
An installation method (AIM) is a procedure approved by water undertakers.
The RPZ AIM provides procedures for both installing and testing of RPZ valves.
A copy of the current version of the RPZ AIM can be found here. It came into force on 1st January 2025.
It is approved the water undertakers in England, Scotland, Wales and Northern Ireland listed on page 2.
Please note: the AIM requires test equipment to meet a minimum specification.
It means there is an RPZ valve on-site which needs to be compliance tested by a competent RPZ tester no later than the test due date in order to comply with the conditions of consent which permitted its installation.
One way to identify a competent RPZ tester is to search using the WaterSafe website.
It is important to act as failure to comply with the requirements specified as a condition of consent may result in the water undertaker taking enforcement action which may include temporarily disconnecting the water supply to the premises and requiring the removal of the RPZ valve. Reconnection shall only be with the agreement of the water undertaker
Contact the local water undertaker for further information.
Details of the proposed work/installation shall be sent to the relevant water undertaker no less than 10 working days before work is due to start. Installing or using RPZ valves without the required consent could result in enforcement action being taken by the water undertaker.
An information leaflet highlighting things those responsible for plumbing systems should be aware of if thinking about installing or already have RPZ valves installed can be found in the Things you need to know about RPZ valves information leaflet.
Please note that failure to provide the minimum level of information required may delay consent. Contact the local water undertaker for further information.
Failure to comply with the requirements specified as a condition of consent may result in the water undertaker taking enforcement action which may include temporarily disconnecting the water supply to the premises and requiring the removal of the RPZ valve. Reconnection shall only be with the agreement of the water undertaker
Regulations & Byelaws which apply include but are not limited to:
Relevant guidance includes but is not limited to:
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