Water Regulations Certificate: When Sellers Need One

The Water Supply (Water Fittings) Regulations 1999 require that certain types of plumbing work are notified to your local water company before work begins. If that work was done correctly, by an approved contractor or with the water company's sign-off, there is a compliance certificate to prove it. If it was not, the buyer's solicitor will want to know why — and what you intend to do about it.

For most property sales, water regulations compliance is not an issue at all. It becomes relevant only when plumbing work has been disclosed on the seller's documentation pack or when the buyer's solicitor raises it during conveyancing enquiries. Even then, it is usually resolved quickly with a certificate, a contractor's self-certification, or an indemnity insurance policy.

What are the Water Supply (Water Fittings) Regulations 1999?

The Water Supply (Water Fittings) Regulations 1999 are the legal framework governing the installation and use of water fittings connected to the public mains water supply in England and Wales. They replaced the older water byelaws that individual water companies had maintained separately. Scotland has its own equivalent legislation under the Water Byelaws 2014.

The regulations have two core objectives:

• Preventing contamination. Ensuring that plumbing installations cannot allow contaminated water to flow back into the mains supply (known as backflow or back-siphonage). This protects public health by keeping the drinking water supply safe.
• Preventing waste. Ensuring that water fittings do not cause unnecessary waste, misuse, or undue consumption of mains water.

The regulations are enforced by your local water company (such as Thames Water, Severn Trent, United Utilities, or whichever company supplies your area). The Water Regulations Advisory Scheme (WRAS) provides guidance and testing for products and materials that come into contact with the public water supply.

What plumbing work requires notification?

Not all plumbing work needs to be notified to the water company. Routine maintenance, repairs, and like-for-like replacements are exempt. The regulations specify that the following types of work must be notified in advance:

• Installing a bidet with an ascending spray. Bidets with ascending sprays pose a backflow contamination risk and are among the most commonly cited notifiable items. A standard bidet without an ascending spray does not require notification.
• Installing an outside tap or garden watering system. Any connection to the mains supply that feeds an external outlet (garden tap, irrigation system, or outside drinking fountain) is notifiable because of the backflow risk from hose connections.
• Unvented hot water storage systems. Any unvented (mains-pressure) hot water cylinder or tank with a capacity exceeding 15 litres must be notified. These systems operate under mains pressure and require specific safety controls and competent installation.
• New water supply to a property. Any new connection from the mains water supply into a building, including a new-build property or a property being connected for the first time.
• Plumbing work in buildings other than a single dwelling. Any plumbing installation in a commercial property, a converted flat, or a building with a shared water supply (such as a house converted into flats) is notifiable regardless of the type of work.
• Swimming pools, ponds, and water features. Any pool, pond, or water feature that is automatically filled from the mains supply.
• Water softeners and treatment equipment. Installing water softeners or other treatment devices connected to the mains supply.
• Connections to shared supply pipes. Any work that involves making a connection to a supply pipe that serves more than one property.

The notification must be made to your water company at least ten working days before the work begins. The water company then has the option to inspect the installation during or after the work.

Work that does not require notification

Most routine domestic plumbing work is exempt from notification. You do not need to notify the water company for:

• Replacing taps, washers, ball valves, or toilet flush mechanisms on a like-for-like basis
• Repairing leaks or fixing existing plumbing
• Replacing a toilet, basin, or bath in the same position using the existing plumbing connections
• Replacing a kitchen sink on existing connections
• Installing or replacing a washing machine or dishwasher connection to an existing supply

If you are selling and only routine maintenance has been carried out, water regulations certificates are not something you need to worry about.

Approved contractors: WaterSafe and WIAPS

The simplest way to ensure plumbing work is compliant — and to avoid problems when selling — is to use an approved contractor. In the UK, there are two relevant schemes:

• WaterSafe. This is the current UK-wide register of approved plumbing contractors, managed by the water industry. WaterSafe-approved contractors are authorised to self-certify notifiable plumbing work, which means they can sign off that the installation complies with the regulations without the homeowner needing to notify the water company separately.
• WIAPS (Water Industry Approved Plumber Scheme). This was the predecessor to WaterSafe and operated along the same lines. If plumbing work was carried out under WIAPS, the contractor's self-certification is still valid.

When a WaterSafe or WIAPS contractor completes notifiable work, they issue a compliance certificate to the homeowner. This certificate is the document you need when selling. If you cannot find the original certificate, you may be able to request a copy from the contractor or check with WaterSafe whether the work was registered.

If the work was carried out by a contractor who was not WaterSafe or WIAPS approved, or as a DIY project, the homeowner should have notified the water company directly before starting. If that notification was not made, the work is technically non-compliant and you will need to address this when selling.

How water regulations come up during a sale

Water regulations compliance typically surfaces in one of three ways during the conveyancing process:

1. The TA6 Property Information Form

The TA6 form, which every seller in England and Wales completes as part of the standard property documentation, includes questions about alterations and improvements made to the property. Section 7 asks about works carried out and whether appropriate consents, approvals, and certificates were obtained. If you disclose plumbing work here — or if the buyer's solicitor suspects from the property details that notifiable work has been done — they may ask for evidence of water regulations compliance.

It is important to disclose plumbing work honestly on the TA6. Attempting to conceal work that is later discovered can expose you to a claim for misrepresentation.

2. Buyer's solicitor enquiries

Even if you do not mention plumbing work on the TA6, the buyer's solicitor may raise additional enquiries about water regulations if they notice, for example, an outside tap in the property photographs, an unvented hot water cylinder in the survey report, or a bathroom that appears to have been recently installed in a converted property. These enquiries are routine and not a sign that the sale is in trouble.

3. The survey or valuation report

If the buyer commissions a homebuyer report or building survey, the surveyor may note the presence of an unvented hot water system, an outside tap, or other features that suggest notifiable work. The surveyor may recommend that the buyer's solicitor verify compliance, which in turn triggers an enquiry to you.

Getting a certificate retrospectively

If notifiable plumbing work was carried out without the required advance notification — a common situation, particularly with outside taps and bathroom installations — you can apply to your water company for a retrospective inspection and compliance certificate. Here is how the process works:

1. Contact your water company. Call or email the water regulations team (sometimes called the water fittings team) at your local water supplier. Explain that plumbing work was carried out without prior notification and that you would like a retrospective inspection.
2. Provide details of the work. The water company will want to know what was installed, when it was done, and who carried out the work. Provide as much detail as you can.
3. Arrange the inspection. The water company will send an inspector to your property. They will check that the installation meets the requirements of the Water Supply (Water Fittings) Regulations 1999. The inspection typically covers backflow prevention, air gaps, pipe materials, and the general standard of the installation.
4. Receive the outcome. If the installation passes, the water company issues a compliance certificate. If it fails, they will tell you what remedial work is needed. Once the remedial work is completed, you can arrange a re-inspection.

The timeline for a retrospective inspection is typically two to four weeks from the initial application, though this varies by water company and their current workload. Inspection fees vary but are usually between £50 and £150. Some water companies carry out the first inspection free of charge.

One important consideration: once you contact the water company, the option of using indemnity insurance (see below) is no longer available, because indemnity policies require that no approach has been made to the relevant authority. Decide which route you want to take before making contact.

Indemnity insurance as an alternative

In many cases, the most practical solution for non-notified plumbing work is an indemnity insurance policy rather than a retrospective certificate. This is particularly common where:

• The work was done some time ago and it would be difficult to arrange a retrospective inspection before exchange
• The work is relatively minor (such as an outside tap) and the risk of enforcement action is negligible
• The seller does not want to risk the water company requiring remedial work that could delay the sale

A water regulations indemnity policy covers the buyer (and their mortgage lender) against the financial risk of the water company taking enforcement action — such as requiring the removal or modification of non-compliant fittings. The policy is a one-off payment, typically costing £20 to £50, and remains in force indefinitely, transferring automatically to future owners.

The critical condition of any indemnity policy is that no approach must have been made to the water company about the work in question. If you have already contacted them, the policy is invalid and you must pursue the retrospective certificate route instead.

Most buyer solicitors and mortgage lenders accept indemnity insurance for water regulations issues. Your solicitor can arrange the policy quickly, often within 24 hours. The cost is usually paid by the seller.

How this compares to building regulations

Sellers sometimes confuse water regulations compliance with building regulations sign-off. They are separate regimes:

Some plumbing work may trigger both regimes. For example, installing an unvented hot water system requires notification to the water company under the Water Fittings Regulations and may also require building regulations approval under Part G (sanitation, hot water safety, and water efficiency) and Part L (conservation of fuel and power) of the Building Regulations. If you used a qualified installer registered with a competent person scheme, they should have handled both sets of requirements.

Specific scenarios sellers encounter

Outside taps

Outside taps are one of the most common triggers for water regulations enquiries. Installing an outside tap is notifiable because a hose connected to an external tap creates a backflow risk — contaminated water from a garden hose, pond, or chemical sprayer could be siphoned back into the mains supply if there is no check valve or double check valve fitted.

If you have an outside tap and cannot show that it was installed by an approved contractor or notified to the water company, the buyer's solicitor will likely ask about it. This is one of the most straightforward issues to resolve with an indemnity policy.

Unvented hot water systems

Unvented hot water cylinders (mains-pressure systems such as Megaflo, Heatrae Sadia, or similar) are notifiable under the Water Fittings Regulations and may also require building regulations sign-off. They must be installed by a qualified engineer (typically G3-qualified for building regulations purposes). If your property has an unvented system, the buyer's surveyor will almost certainly note it, and the solicitor will ask for evidence of compliant installation.

If you have the installer's commissioning certificate and a benchmark log showing annual servicing, this should satisfy the enquiry. If you do not, a retrospective water company inspection or indemnity insurance will be needed.

Bathroom and kitchen installations

A straightforward like-for-like replacement of bathroom or kitchen fittings is not notifiable. However, if the installation involved moving plumbing to new positions, adding new outlets, or fitting any of the notifiable items listed above (such as a bidet with an ascending spray), notification was required. In practice, many bathroom and kitchen refurbishments are done without notification because the homeowner and contractor were not aware of the requirement. This is common and is usually resolved with an indemnity policy.

Properties with private water supplies or septic tanks

The Water Supply (Water Fittings) Regulations 1999 apply specifically to fittings connected to the public mains water supply. If your property has a private water supply (such as a borehole or spring), the regulations do not apply in the same way, though the Private Water Supplies Regulations 2016 impose separate requirements. If your property has a septic tank or private drainage, that is a separate matter from water supply regulations and is dealt with under different environmental legislation.

Practical impact on your sale

In the context of everything that can go wrong during a property sale, water regulations compliance is typically a minor issue. It rarely causes sales to fall through and is almost always resolvable. Here is a realistic assessment of its impact:

• If you have a certificate or contractor self-certification: No impact at all. Provide the certificate to your solicitor as part of your documentation pack and the matter is closed.
• If you need a retrospective certificate: Expect a delay of two to four weeks while the water company arranges an inspection. This can usually run in parallel with other conveyancing steps, so it may not extend your overall timeline.
• If you use indemnity insurance: Minimal impact. The policy can be arranged within 24 hours and costs under £50. Most buyer solicitors and lenders accept it without further questions.
• If the buyer's solicitor insists on a certificate and the work fails inspection: This is the worst-case scenario. You would need to carry out remedial work and arrange a re-inspection, which could add several weeks. In practice, this is rare for standard domestic plumbing.

The key to preventing this issue from causing delay is to identify it early. When completing your TA6 disclosure form, think carefully about any plumbing work that has been done to the property. If you know that notifiable work was carried out without proper certification, address it proactively — either by arranging a retrospective certificate before you list, or by having your solicitor prepare an indemnity policy ready for when the buyer's side raises the question.

What to prepare before listing

If you know or suspect that notifiable plumbing work has been carried out on your property, take these steps before you put it on the market:

1. Identify any notifiable work. Walk through your property and note any outside taps, unvented hot water cylinders, bidets with ascending sprays, water softeners, or recently installed bathrooms where plumbing was moved.
2. Locate existing certificates. Check your paperwork for compliance certificates from WaterSafe or WIAPS contractors, or confirmation of notification from the water company. Also check for building regulations certificates for unvented hot water systems.
3. Decide on your approach. If you have certificates, include them in your document pack. If you do not, decide whether to pursue a retrospective certificate from the water company or plan for indemnity insurance. Remember that contacting the water company rules out the indemnity option.
4. Brief your solicitor. Tell your solicitor about any plumbing work and your preferred approach so they can prepare the appropriate response or policy in advance.

Sources

• Water Supply (Water Fittings) Regulations 1999 — legislation.gov.uk
• Water Regulations Advisory Scheme (WRAS) — wras.co.uk
• WaterSafe — watersafe.org.uk
• Water Industry Act 1991 — legislation.gov.uk
• Building Regulations 2010, Approved Document G (sanitation, hot water safety and water efficiency) — gov.uk
• Private Water Supplies Regulations 2016 — legislation.gov.uk
• Law Society — Property Information Form (TA6), 4th edition
• RICS Home Survey Standard, 4th edition — rics.org

Frequently asked questions