Water Regs UK has officially published revised guidance on the installation and testing of RPZ valves (Reduced Pressure Zone valves), following a public consultation.
The updated document, known as the RPZ Approved Installation Method (RPZ AIM), came into force on 1st January 2025 and sets out the correct requirements for installing and commissioning RPZ valves in line with legal water safety regulations across the UK.
These updates are particularly important for plumbing and water compliance professionals, as they introduce new minimum standards for testing equipment, clearer guidance on acceptable testing methods, and new competency revalidation requirements for RPZ testers.
What is the RPZ AIM?
The RPZ AIM (Approved Installation Method) outlines how RPZ valves must be installed and tested to comply with:
- The Water Supply (Water Fittings) Regulations (England & Wales)
- The relevant Byelaws in Scotland
These legal requirements apply to all premises that have, or will have, a mains water supply. The purpose is to protect drinking water by preventing:
✅ Contamination
✅ Misuse of the water supply
✅ Waste or undue consumption
✅ Erroneous measurement
RPZ valves are essential backflow prevention devices and play a key role in protecting public water supplies from contamination risks.
What Has Changed in the 2025 RPZ AIM Update?
The new edition introduces important updates to ensure higher testing standards and more accurate evidence-based measurements.
The main changes include:
- New minimum requirements for RPZ test equipment
- Clearer approved testing procedures
- A requirement for RPZ testers to periodically demonstrate competence
Water Regs UK has also published separate detailed guidance specifically outlining the new equipment specifications.
New Minimum Requirements for RPZ Test Equipment
One of the biggest changes is the introduction of a new minimum specification for RPZ valve test equipment.
Important deadline:
📅 RPZ valve testers have until 30th June 2026 to replace equipment that does not meet the new requirements.
This gives the industry time to transition to compliant equipment without disrupting essential testing work.
Single Tube Manometers No Longer Allowed
From 1st January 2025, testing using a single tube manometer is no longer acceptable.
This is a significant change for many testers, as single tube manometers have been widely used in the past.
Temporary Use of U-Tube Manometers (Until 1st January 2026)
There is a transition period for U-tube manometers.
Until 1st January 2026, RPZ testers may continue using a U-tube manometer, but only if they follow the correct procedures outlined in:
- Regulator Test Code Sheet (TCS) 1111.13, or
- Clause 9.5.2 of BS EN 12726:2023
After this date, testers must ensure they are fully compliant with the updated testing equipment requirements.
New Competency Revalidation Requirements (Every 5 Years)
Another major change is the introduction of a clear revalidation requirement for RPZ testers.
RPZ valve testers will now be expected to demonstrate competence by revalidating their qualification every 5 years.
In most cases, this will be completed through reassessment rather than retraining, making the process more streamlined for qualified engineers.
Revalidation rules depend on when you qualified:
If you qualified after November 2021:
You should revalidate your qualification every 5 years from your certification date.
If you completed conversion training prior to December 2020:
You must revalidate your qualification by 31st December 2026.
Why Have These Changes Been Introduced?
Paul Millard, Technical Manager for Water Regs UK, explained that the aim is to improve standards across the industry and ensure accurate and consistent testing results.
He stated that the updates will:
- Improve overall testing standards
- Ensure accurate evidence-based measurements
- Align the UK with good practice adopted in countries such as Australia and the USA
- Clarify roles and responsibilities for those involved in RPZ testing
Water Regs UK has also encouraged all testers to ensure they fully understand what is expected of them, as sufficient time has been given to meet the new requirements.
Who Can Carry Out RPZ Valve Testing?
Water Regs UK has reinforced that on-site testing should only be carried out by someone who is:
✅ Fully trained
✅ Properly qualified
✅ Recognised as competent in RPZ commissioning and compliance testing
This ensures public water systems remain protected and compliance standards are maintained across all installations.
What Should Engineers and Businesses Do Next?
If you install, commission or test RPZ valves, it is vital to:
- Review your current test equipment and confirm it meets the new minimum specification
- Stop using single tube manometers immediately (from 1 Jan 2025)
- Ensure U-tube testing follows the approved methods (until 1 Jan 2026)
- Plan ahead for replacement equipment before 30 June 2026
- Check your qualification date and schedule your revalidation before your deadline
Need More Information?
For official guidance and FAQs, Water Regs UK provides further details here:
- RPZ FAQs and guidance: Water Regs UK website: Water Regs UK Limited – RPZ
- Water company contact details: Water Regs UK water company contacts: Water Regs UK Limited – Water Company Contacts
RPZ Training & Revalidation Support
At Hampshire Training & Assessments, we support plumbing and water industry professionals with compliance-based training and guidance to ensure you remain up to date with the latest regulatory requirements.
HTAA’S RPZ Valve course…
RPZ Valve Commissioning, Inspection & Testing – Hampshire Training & Assessments
If you need support understanding the new RPZ AIM guidance, equipment changes, or competency revalidation requirements, feel free to get in touch with our team.
