The Water Industry Approved Plumbers’ Scheme, almost always shortened to WIAPS, is the UK’s largest approved contractor scheme for plumbing and water fittings work. It is run by Water Regs UK on behalf of the water companies, and it gives qualified installers a recognised way to certify that their work meets the Water Supply (Water Fittings) Regulations 1999.
For a scheme that touches so much plumbing and water connection work, WIAPS is surprisingly poorly explained online, and the official information is scattered and, in places, out of date. This guide pulls it together: what WIAPS is, who runs it, the sectors it covers, what a WIAPS certificate actually means, and how it sits alongside WRAS and WaterSafe. McFadden holds WIAPS accreditation, which is why we have set the detail out properly here.
What is WIAPS?
WIAPS is an approved contractor scheme established under the Water Supply (Water Fittings) Regulations 1999 (and the equivalent byelaws in Scotland). These regulations require that plumbing and water fittings work meets defined standards to protect the public water supply from contamination, waste and misuse. The scheme accredits installers who have proven they understand and work to those rules.
The core benefit of approval is self-certification. An approved contractor can carry out certain work without giving the water company advance notification, and on completion issues a Certificate of Compliance confirming the work meets the regulations. WIAPS is the largest of the UK’s approved contractor schemes and the one run directly by the water companies. The others, which sit alongside it, are run by professional and trade bodies: the Chartered Institute of Plumbing and Heating Engineering (CIPHE), the Association of Plumbing and Heating Contractors (APHC), and the Scottish and Northern Ireland Plumbing Employers’ Federation (SNIPEF).
Who runs WIAPS, and how it differs from WRAS
WIAPS is administered by Water Regs UK on behalf of the water companies in England and Wales. This is the single most muddled point about the scheme, so it is worth being precise, because even AI tools and some industry pages get it wrong and attribute WIAPS to WRAS.
Until 2021, the Water Regulations Advisory Scheme (WRAS) was a single body covering several water regulations services. In 2021 it was split into two separate organisations:
- Water Regs UK took on the regulatory guidance and the approved contractor side, which is what administers WIAPS.
- WRAS, now the Water Regulations Approval Scheme, kept the familiar WRAS logo and runs the approvals process for water fittings and materials.
So the distinction is simple once you know the split: WRAS approves products and fittings, while Water Regs UK approves the people and businesses installing them, through WIAPS. A WIAPS certificate and a WRAS product approval are two different things.
What WIAPS covers: the sectors
WIAPS is often described as a plumbers’ scheme, but it accredits several different types of installer, each with its own defined scope. This matters, because an approved contractor can only certify the type of work their sector covers.
WIAPS approved contractor sectors
| Sector | What they can certify |
|---|---|
| Plumbers | All parts of a plumbing system, from the external supply pipe through to the kitchen and bathroom taps |
| Groundworkers (Water Supply Pipe Installers) | The underground supply pipe serving a property, up to the internal stop valve |
| Catering Installers | Connection of commercial kitchen and catering equipment to the mains supply |
| Point of Use Installers | Cold water chillers and similar units connected directly to the mains |
| RPZ Valve Testers | Commissioning and testing of reduced pressure zone (RPZ) backflow prevention valves |
There is also a more recent Education sector, which provides digital learning resources rather than installation approval. The Groundworker sector, covering the external supply pipe up to the stop valve, is the one most relevant to water mains and connection contractors as opposed to internal plumbers.
What a WIAPS certificate means
The practical value of WIAPS is in two linked things: the notification exemption and the Certificate of Compliance.
Normally, certain plumbing and water fittings work has to be notified to the water company before it starts, so they can check it. An approved contractor can skip that advance notification for eligible work, which saves time on the job. In exchange, on completion they must issue a Certificate of Compliance confirming the work meets the Water Fittings Regulations, and send a copy to the local water company as well as giving one to the client. For the sector schemes (groundworkers, catering, and so on), it is worth noting that the notification exemption is generally limited to the alteration or extension of systems rather than every type of work.
How a contractor joins WIAPS
Approval is not automatic. To become a WIAPS approved contractor, a business needs installers who hold a recognised water regulations qualification alongside the relevant trade qualification for the work they want to certify. Beyond qualifications, members must carry public liability insurance, operate a complaints process, and agree to be audited periodically by the local water company to confirm standards are being kept up.
On cost, membership is free for the Plumber sector. For businesses holding one of the sector memberships (groundworker, catering, point of use or RPZ), there is an annual fee of £78 plus VAT, the same regardless of how many approved individuals the business has.
WIAPS, WaterSafe and the wider picture
WIAPS membership automatically includes registration on WaterSafe, the national online register that brings the approved contractor schemes together under one searchable directory. So a WIAPS approved business also appears on WaterSafe, where customers and water companies can verify an installer by postcode.
In terms of coverage, WIAPS operates across all of England and Wales except the area served by Anglian Water, which runs its own approved plumber scheme. The scheme is also consolidating rather than standing still: from 1 April 2025 the WaterMark scheme, previously run by Severn Trent and Hafren Dyfrdwy, was absorbed into WIAPS, managed by Water Regs UK, so that installers in those regions are covered by a single scheme rather than holding dual memberships.
For the equivalent accreditation on the water mains and self-lay side of the industry, rather than internal plumbing, see our guide to WIRS accreditation.
WIAPS: common questions
WIAPS stands for the Water Industry Approved Plumbers’ Scheme. It is a UK approved contractor scheme that accredits installers to certify their plumbing and water fittings work as compliant with the Water Supply (Water Fittings) Regulations 1999.
WIAPS is administered by Water Regs UK on behalf of the water companies in England and Wales. It is not run by WRAS. Water Regs UK took on the approved contractor role when the former Water Regulations Advisory Scheme was split in 2021.
No. A WIAPS Certificate of Compliance confirms that an approved contractor’s installation meets the Water Fittings Regulations. WRAS approval, now run by the Water Regulations Approval Scheme, certifies that a product or fitting itself meets the regulations. One covers the work, the other covers the materials.
A WIAPS approved groundworker, also called a Water Supply Pipe Installer, is approved to work on the underground supply pipe serving a property, up to the internal stop valve. It is the WIAPS sector relevant to external water supply and connection work rather than internal plumbing.
Yes. WIAPS is current and is the UK’s largest approved contractor scheme. It is in fact expanding: from 1 April 2025 the WaterMark scheme run by Severn Trent and Hafren Dyfrdwy was absorbed into WIAPS to simplify membership for installers in those regions.
