WIAPS — Water Industry Approved Plumber Scheme
The third rulebook, and the one nobody mentioned
What WIAPS is
WIAPS approval lets a plumber self-certify that water fitting installations comply with the Water Supply (Water Fittings) Regulations 1999. It costs around £200 a year, renewing annually, which makes it the cheapest scheme on this site by a distance.
It applies to work involving connections to the mains supply, backflow prevention devices, and other regulated fittings.
Most plumbers hold a mental map of compliance with two things on it: Gas Safe for gas, and Building Regulations for the building. The Water Fittings Regulations are a third, separate legal regime, with their own requirements, their own notification route and — crucially — a different body to notify. Not building control. The water undertaker for the area.
That is the single most useful thing on this page, because a plumber who does not know the regime exists is not deliberately ignoring it. They have simply never been told there was a third rulebook.
What the regulations are actually protecting
Understanding the purpose makes the requirements obvious rather than arbitrary.
The Water Fittings Regulations exist to stop the public mains being contaminated. Everything else follows from that. Backflow — water flowing the wrong way, from a property back into the supply — is the central risk, and the regulations classify fluid categories by how dangerous they would be if they got back into the main.
That is why the rules care intensely about things a plumber might otherwise treat as detail: the air gap on a cistern, the type of check valve on an outside tap, whether a hose connection could siphon back, how a commercial system with chemicals in it is separated from the drinking supply.
It also explains why the water undertaker is the notifier rather than building control. Building control cares whether the building is safe. The water company cares whether its main is safe, and those are different questions about the same pipework.
What you need to get it
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Water regulations knowledge.
Demonstrate knowledge of the Water Supply (Water Fittings) Regulations 1999 — pass the water regulations assessment, or hold a recognised qualification covering them. Evidence: the assessment pass or qualification.
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A plumbing qualification.
NVQ Level 2 or 3 in Plumbing, or equivalent. Evidence: the certificate.
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Application through an approved registration body.
WIAPS is administered through approved bodies rather than as a single central application. Evidence: the completed application.
What you have to keep doing
Renew annually and pay the fee.
Notify notifiable work to the local water authority within the required timescales. Note the phrase — local water authority. A plumber who has spent years notifying building control through a different scheme will reach for the wrong route the first time.
It is £200, and it is a commercial argument rather than a cost
At two hundred pounds a year this is not a scheme anyone needs a business case for. The interesting question is why so few plumbers hold it, and what the ones who do should say about it.
The answer to the first is visibility. There is no equivalent of the Gas Safe advertising campaign for water regulations, so neither plumbers nor customers have the regime front of mind, and demand for it is quiet.
That quietness is precisely the opportunity. Commercial and landlord work is where water regulations bite hardest — a pub cellar, a dental practice, a care home, a building with a commercial kitchen all involve fluid categories that a domestic installer never meets. The buyers of that work generally do know the regime exists, because their own compliance people have told them, and they have a genuinely hard time finding a plumber who can speak to it.
So the marketing move is not “we are WIAPS approved” on a badge row. It is saying, on the page where a commercial buyer lands, that you work to the Water Fittings Regulations, that you understand fluid categories and backflow protection, and that you can self-certify and notify. Almost nobody in the trade writes that sentence, and the people it is aimed at are searching for exactly it.
The mistakes we see most
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Assuming Building Regs cover it.
They do not. It is a separate regime with a separate notifier.
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Notifying the wrong body.
Water undertaker, not building control — an easy reflex to get wrong.
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Treating backflow as a technicality.
It is the entire point of the regulations and the thing an inspector will look at first.
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Never mentioning it.
Commercial buyers actively look for this and mostly cannot find it.
One job, three regimes
The clearest way to see why this scheme is under-held is to follow a single ordinary job.
A heating engineer replaces a boiler and fits an unvented hot water cylinder, connecting to the mains. That is one visit, one invoice, and one customer — and it sits inside three separate compliance regimes at once.
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Gas Safe
Covers the gas side, with its own registration and its own notification.
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Building Regulations Part G
Covers the unvented cylinder — sanitation and hot water safety — notified to building control through a competent person scheme.
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The Water Fittings Regulations
Cover the connection to the mains and any backflow protection, notified to the water undertaker.
Three rulebooks, three notifiers, and one engineer who is usually registered for the first, sometimes for the second, and rarely for the third.
Nobody designed it to be confusing; the regimes grew separately because they protect different things — the occupant from gas, the occupant from scalding and stored pressure, and everybody else from a contaminated main. But the practical effect is that a competent engineer can complete a job properly and still leave one of the three unnotified without ever making a decision to.
The useful response is not anxiety, it is a map. Work out which of the three each type of job you take on touches, and register for the ones you are actually in. For most heating engineers that is all three, and the third is the cheapest of them by a wide margin.
Where this lands in Gaffer
Approval renewal sits against the business with a reminder before it expires, alongside the other scheme dates rather than in a different place — the whole problem with a third regime is that it lives in a third folder.
Notifiable installations are logged against the property with the date and what was fitted, so the notification window is something the system watches rather than something that depends on remembering which of two authorities wanted telling.
Questions plumbers ask
Is WIAPS legally required? The regulations are legally binding on the work. WIAPS is the route to self-certifying compliance rather than involving the water undertaker each time.
Does Gas Safe or a Part P scheme cover water regs? No. Different regime, different scheme, different notifier.
Is £200 worth it for domestic work? For straightforward domestic work the case is thinner. For commercial, landlord and any premises with real backflow risk, it is the qualification the buyer is looking for.
Who do I notify? The local water authority, within the timescales they set — not building control.
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