Water Regulations: What Plumbers Need to Know About WRAS and Backflow Prevention

Summary

The Water Supply (Water Fittings) Regulations 1999 replaced the former Water Byelaws and apply to every premises supplied with water by a water undertaker in England and Wales (Scotland has equivalent Byelaws). They place legal duties on owners, occupiers, and installers to ensure that plumbing systems do not contaminate the public water supply, primarily through correct backflow prevention. The regulations classify fluids into five risk categories (1-5) and mandate corresponding levels of backflow protection, from simple check valves up to air gaps. WRAS (Water Regulations Approval Scheme) provides a product approval scheme that, while not a strict legal requirement in itself, is the standard way to demonstrate that fittings and materials comply. Failure to comply is a criminal offence under the Water Industry Act 1991, enforceable by the local water undertaker, and can result in prosecution, fines, disconnection of supply, or mandatory removal and reinstallation of non-compliant work.

Key Facts

• The regulations apply to all premises connected to the public mains supply, including domestic, commercial, and industrial properties.
• It is the legal responsibility of the owner or occupier to ensure compliance; where they fail to do so, the duty falls on the installer or plumber.
• Regulation 4 requires that every water fitting installed shall be of an appropriate quality and standard, be suitable for the circumstances, and comply with the requirements of Schedule 2.
• Regulation 5 requires advance notification to the water undertaker for specific categories of plumbing work (see Notification Requirements below).
• Approved contractors (WaterSafe/WIAPS registered) may self-certify certain categories of work without prior notification, but must still issue a compliance certificate to the customer and the water company.
• Water companies have 10 working days to respond to a notification. If no response is received, the installer may proceed.
• WRAS product approval lasts for a maximum of 5 years and must be renewed through retesting.
• Water undertakers have the power to enter premises, inspect installations, and take enforcement action including prosecution under the Water Industry Act 1991.

Detailed Guidance

What is WRAS approval and do products legally need it?

WRAS (Water Regulations Approval Scheme) is an independent UK certification body that tests plumbing products and materials against the requirements of Schedule 2 of the Water Supply (Water Fittings) Regulations 1999. Testing covers mechanical performance, contamination of water quality (taste, odour, appearance), and the potential for promoting microorganism growth.

WRAS approval is not itself a legal requirement. The law requires that all water fittings comply with the regulations; WRAS approval is simply the most widely recognised and accepted way to demonstrate that compliance. In practice, water company inspectors will expect to see WRAS-approved products, and specifying non-WRAS-approved fittings places the burden of proof on the installer to demonstrate compliance by other means.

There are two types of WRAS approval:

• WRAS Product Approval -- mechanical and performance testing of the complete fitting (e.g. a tap, valve, or cistern).
• WRAS Material Approval -- testing of materials that come into contact with wholesome water (e.g. pipe compounds, lubricants, sealants, rubber seals).

Both approvals are valid for a maximum of 5 years and are listed in the WRAS Product and Materials Directory at wrasapprovals.co.uk.

When must products be WRAS approved? Any product or material that will carry or receive water from the public mains supply should ideally hold current WRAS approval. This includes pipes, fittings, taps, valves, cisterns, cylinders, water heaters, pumps, water treatment units, washing machines, dishwashers, and any seals, gaskets, or jointing compounds in contact with mains water.

What are the five fluid categories and why do they matter?

The regulations classify all fluids into five categories based on the risk they pose to human health if they were to flow back into the mains supply. The fluid category determines the minimum level of backflow protection required.

The fluid category of an application is always determined by the highest risk present, not the typical or intended use. If there is any doubt, assume the higher category.

What backflow prevention devices are required for each fluid category?

Backflow occurs through either back-siphonage (negative pressure in the mains drawing fluid backwards) or back-pressure (downstream pressure exceeding mains pressure). The type of backflow device required depends on both the fluid category and whether the risk is from back-siphonage, back-pressure, or both.

Key points on device selection:

• Single check valves (Type EA/EB): Sufficient only for Fluid Category 2. A single check valve on its own is never adequate for Category 3 or above.
• Double check valves (Type EC/ED): The standard protection for Fluid Category 3. Commonly installed on domestic washing machine and dishwasher connections, heating system fill loops, and shower hoses.
• RPZ valves (Type BA): Required for Fluid Category 4. These are mechanical devices containing two independently acting check valves with a pressure-monitored relief valve between them. RPZ valves must be tested annually by a competent person and must be installed with adequate drainage for the relief valve discharge. They must never be installed in a confined space without adequate drainage.
• Air gaps (Type AA/AB): The only acceptable protection against back-pressure at Fluid Category 5. A Type AA air gap must have a vertical distance of at least 20mm or twice the internal diameter of the inlet pipe, whichever is greater. A Type AB air gap includes a weir overflow to prevent the receiving vessel from flooding.
• Pipe interrupters (Type AD/DC): Protect against back-siphonage only at Fluid Category 5 -- they do not protect against back-pressure.

When must you notify the water company?

Regulation 5 requires advance written notification to the local water undertaker before commencing the following categories of work:

1. The erection of a building or other structure (not being a pond or swimming pool)
2. The extension or alteration of a water system on any premises other than a house
3. A material change of use of any premises
4. Installation of any of the following:
   • A bath with a capacity exceeding 230 litres (measured to the centre line of the overflow)
   • A bidet with an ascending spray or flexible hose
   • A shower unit connected to a supply pipe (single or multi-head)
   • A pump or booster drawing more than 12 litres per minute
   • A water treatment unit that produces a waste water discharge or requires water for regeneration/cleaning (this includes water softeners that regenerate with brine)
   • A reverse osmosis unit
   • A reduced pressure zone (RPZ) valve assembly or other mechanical device for protection against Fluid Category 4 or 5
   • A garden watering system unless designed to be operated entirely by hand
   • Any water system laid outside a building at a depth of less than 750mm or more than 1350mm below ground level
5. Construction of a pond or swimming pool exceeding 10,000 litres capacity that is designed to be automatically replenished from the mains supply

The notification must include:

• Name and address of the person giving notice (and the person to receive consent, if different)
• Description of the proposed work and any change of use
• A plan of the relevant part of the premises
• A diagram of the proposed pipework and fittings

The water company has 10 working days to respond. If no response is received within that period, the work may proceed. If consent is given subject to conditions, those conditions are legally binding.

Approved contractor exemption: Plumbers registered with an approved contractor scheme (such as WaterSafe or WIAPS -- Water Industry Approved Plumber Scheme) may self-certify certain categories of notifiable work without waiting for prior consent. They must, however, issue a compliance certificate to both the customer and the water company within 30 days of completing the work.

What are the most common compliance mistakes?

1. No backflow protection on outside taps. A standard hose union bib tap connected to the mains is a Fluid Category 3 risk (the hose end may be submerged in contaminated water). It requires at minimum a double check valve or, preferably, a Type HA hose union backflow preventer. This is the single most common deficiency found during water company inspections.

2. Missing or incorrect protection on heating system fill loops. A permanent connection between the mains supply and a central heating system (which contains chemical inhibitors) is a Fluid Category 3 risk. Temporary fill loops with a double check valve are acceptable, but the fill loop must be disconnectable -- a permanent connection without adequate backflow protection is a contravention.

3. Incorrect bidet installation. A bidet with an ascending spray or flexible hose (over-rim or below-rim) in a household bathroom is a Fluid Category 5 risk if the spray can be submerged in contaminated water. This requires either a Type AA/AB air gap to the bidet supply or a dedicated supply from a Category 5 protected storage cistern. Many installers incorrectly treat bidets as Category 3.

4. Failing to notify. Many plumbers are unaware that installing a standard combi-fed shower, a water softener, or an automatic garden watering system are all notifiable works under Regulation 5. Non-notification can result in enforcement action against both the installer and the property owner.

5. Non-WRAS-approved products. Using fittings, pipes, or materials that do not hold current WRAS approval. This is particularly common with internet-sourced imported fittings and with jointing compounds or PTFE tapes that are not WRAS material approved.

6. RPZ valves installed without drainage. RPZ valves must be installed where the relief valve can discharge freely to a tundish or drain. Installing an RPZ valve in a location where discharge cannot be safely managed defeats its purpose and creates a flood risk.

7. Dead legs and stagnant water. Capped-off pipework or oversized systems that create dead legs allow water to stagnate, promoting bacterial growth (including Legionella). The regulations require that systems are designed to avoid stagnation (Schedule 2, Paragraph 8).

8. Not maintaining annual RPZ valve testing. RPZ valves (Type BA) are verifiable devices that must be tested at least annually by a competent person. Failure to test is a contravention. Test records must be kept and should be available for water company inspection.

Frequently Asked Questions

Can I do plumbing work without being a registered plumber?

Yes. Unlike gas work (which requires Gas Safe registration by law), there is no legal requirement to be a registered plumber to carry out plumbing work. However, the person carrying out the work is legally responsible for ensuring it complies with the Water Supply (Water Fittings) Regulations 1999. Being registered with an approved contractor scheme such as WaterSafe or WIAPS provides the benefit of self-certification and demonstrates competence to customers and water companies. For work on unvented hot water systems, a separate G3 qualification is legally required under Building Regulations Part G.

Do I need to notify for a standard bathroom refit in a house?

Not necessarily. A straightforward like-for-like replacement of sanitaryware in a domestic property (replacing an existing bath, basin, or WC) generally does not require notification, provided no notifiable items are being installed. However, if the refit includes a bidet with an ascending spray or flexible hose, or a new shower connected to the supply pipe, notification is required. If you are a WaterSafe/WIAPS approved contractor, you can self-certify rather than waiting for prior consent.

What happens if a water company inspector finds non-compliant work?

The water undertaker has powers under the Water Industry Act 1991 to serve a notice requiring the owner or occupier to make alterations within a specified period. If the notice is not complied with, the undertaker may carry out the work themselves and recover the costs. In serious cases -- particularly where there is an immediate risk to public health -- the undertaker can disconnect the supply. Prosecution for contravention of the regulations can result in a fine of up to GBP 1,000 per offence, with a continuing daily penalty for ongoing non-compliance. The installer, owner, and occupier can all be prosecuted.

Is a filling loop on a sealed heating system notifiable?

A standard filling loop on a domestic sealed heating system is not itself a notifiable item under Regulation 5 (it does not appear in the notification table). However, it must still comply with the regulations: the loop must incorporate a double check valve (Fluid Category 3 minimum) and should be a temporary, disconnectable connection. A permanent, non-disconnectable filling loop contravenes Schedule 2 regardless of whether notification was required.

Regulations & Standards

• Water Supply (Water Fittings) Regulations 1999 (SI 1999/1148) -- the primary legislation covering plumbing installations in England and Wales. Regulation 4 (requirements for water fittings), Regulation 5 (notification), Schedule 1 (fluid categories), Schedule 2 (requirements for water fittings).

• Water Supply (Water Fittings) (Amendment) Regulations 1999 (SI 1999/1506) -- minor amendments to the 1999 regulations.

• Water Byelaws 2014 (Scotland) -- equivalent requirements for Scotland, administered by Scottish Water.

• Water Supply (Water Fittings) Regulations (Northern Ireland) 2009 -- equivalent requirements for Northern Ireland.

• Water Industry Act 1991 -- the parent Act providing enforcement powers to water undertakers.

• BS EN 1717:2000 -- Protection against pollution of potable water in water installations and general requirements of devices to prevent pollution by backflow (European standard).

• BS 6700:2006+A1:2009 -- Design, installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages.

• Building Regulations Part G (England) / Part G (Wales) -- sanitation, hot water safety and water efficiency requirements.

• The Water Supply (Water Fittings) Regulations 1999 -- legislation.gov.uk

• WRAS Approvals -- Official Product and Material Approvals

• Water Regs UK -- Different Types of Backflow Prevention

• Water Regs UK -- Backflow Protection

• WRAS Fluid Categories Explained -- Dutypoint

• Category 5 Water Regulations and Backflow Prevention -- Dutypoint

• Backflow Basics -- Reliance Valves

• WaterSafe -- Water Fittings Regulations FAQ

• Yorkshire Water -- Regulation 5 Notification

• Affinity Water -- Water Fittings Regulations Explained

• Thames Water -- Water Supply (Water Fittings) Regulations 1999 Code of Practice (January 2025)

• pipe sizing -- Domestic plumbing pipe sizing guide

• compression fittings -- Fitting types and WRAS compliance

• unvented cylinders -- G3 qualification and safety requirements