Plumbing systems

This section explains the requirements for installing a new plumbing system under the current water regulations. This includes the fittings, the design of the system and the prevention of backflow.

Installing, modifying and maintaining domestic plumbing systems

This booklet provides guidance on some of the most common Water Fittings Regulations issues encountered in the home

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Meeting the regulations

Plumbing systems must be designed, installed and maintained to meet the Regulations’ requirements.

Plumbing materials and fittings must be of a suitable standard. Although it is not illegal to sell unsuitable fittings and appliances, it would be illegal to install them.


Approved Water Fittings

The company has the duty to ensure that;

Any water fitting, which when installed, will carry or receive water from the public mains water supply in the UK, complies with the Regulation 4 and is installed in such a way that it complies with the Water Supply (Water Fittings) Regulations. This requires that a water fitting should be of an appropriate quality and standard and not able cause waste, misuse, undue consumption or contamination of the water supply.

Water Regulations Officers inspect installations, identify risks and enforce water fittings compliance by verifying and assuring that:

  1. Fittings are of a sufficient quality and standard; ie,
  2. Bears an appropriate CE marking in accordance with the directive;
  3. Conforms to an appropriate harmonized standard or European technical approval
  4. Conforms to an appropriate British standard, bears the UKCA Mark (UK Conformity Assessed) or some other national specification of an EEA State which provides an equivalent level of protection and performance
  5. Conforms to a specification approved by the Regulator
  6. Be suitable for the circumstances in which they are;
  7. Fitted, connected, altered, repaired or disconnected in a workmanlike manner
  8. Installed and used in accordance with an appropriate British standard, European technical approval or some other national specification of an EEA State which provides an equivalent level of protection and performance.
  9. Installed to a specification approved by the regulator, or to a method of installation approved by the water undertaker.

Water Regulation Officers will consider all water fittings. However the testing of sufficiency and suitability of products, materials and fittings in the field is almost impossible without specialist equipment. Therefore Officers will conduct visual inspections of water fittings and systems, conduct reasonable enquiries and rely upon their experience and knowledge of the water regulations to either accept or reject installations.

There are a number of water fittings approval companies that test and certify water fittings and Water Undertakers accept these certifications as proof of compliance with Regulation 4. Current known approvers are: KIWA, NSF, WRAS.



Plumbing must be properly installed and maintained to:

  • Protect water quality
  • To ensure safety
  • Allow ease of access for maintenance
  • Allow detection of leakage
  • Give protection against damage or freezing etc.

An approved contractor will guarantee compliance of the new installation. Find an approved plumber.

The Regulations do not apply to existing water fittings. Any plumbing system or water fitting which was installed lawfully under the Water Supply Byelaws before the Regulations came into force on 1 July 1999 can continue to be used, even if its installation would not now be permitted.


Prevention of backflow

Where water or water-using appliances are used with fluids or materials which could contaminate the water supply there must be adequate protection to prevent backflow into other parts of the system.

The Regulations specify five Fluid Risk Categories describing types of contaminant, and detailing the appropriate type of prevention device that must be fitted to guard against backflow of contaminated water.