8.1 Approved Materials and Fittings

Why Material Choice Is a Hygiene Issue

Every surface that a drop of wholesome water touches on its way to a customer's tap becomes part of the water supply. That includes the new MDPE service pipe, the emergency repair coupling, the rubber washer inside it, the valve seat, the thread sealant and even the smear of jointing lubricant that eased the joint home. If any one of those materials is wrong, the water itself becomes wrong — which is why the National Water Hygiene assessment treats approved materials as a hygiene topic, not a plumbing detail.

Unapproved or unsuitable materials degrade water quality in five well-understood ways:

• Leaching — substances dissolve out of the material and into the water, for example non-approved alloys or coatings shedding metals into the supply.
• Taint — the material imparts a taste or odour; customers complain about metallic or TCP-like flavours long before any laboratory detects a health risk.
• Corrosion and debris — unsuitable metals corrode and shed particles that travel to the tap or settle in the main.
• Microbial growth — some rubbers, plastics, lubricants and sealants provide nutrients that support biofilm and bacterial growth on the wetted surface.
• Physical failure — a material that softens, swells or perishes can block the pipe, leak, or create the very breach that lets contamination in.

What "Approved" Means in Law

The legal test sits in regulation 4 of the Water Supply (Water Fittings) Regulations 1999. Every water fitting must be of an appropriate quality and standard and suitable for the circumstances in which it is used. A fitting is of an appropriate quality and standard only if it:

• conforms to an appropriate British Standard, or some other national specification that provides an equivalent level of protection and performance; or
• conforms to a specification approved by the regulator.

Older summaries also list CE marking and harmonised European standards. Those routes have been removed from regulation 4: the harmonised-standard route in 2013 and the CE-marking route from 31 December 2020. A CE mark on its own therefore no longer proves that a fitting complies.

Every water fitting must also comply with Schedule 2 to the Regulations, and every water fitting must be installed, connected, altered, repaired or disconnected in a workmanlike manner — conforming to an appropriate British Standard, a specification approved by the regulator, or a method of installation approved by the water undertaker.

WRAS and the Approvals Schemes

The Water Regulations Advisory Scheme (WRAS) runs the WRAS Approval scheme for products and materials suitable for contact with wholesome water, and its approvals sit in a searchable public directory at wras.co.uk. Advice on the Regulations themselves, such as guidance on backflow arrangements, is published by Water Regs UK at waterregsuk.co.uk. At Blue Card level you need awareness, not expertise:

• WRAS Product Approval covers a complete fitting — a valve, tap or coupling — tested as a whole assembly.
• WRAS Material Approval covers the non-metallic materials themselves. Approval is granted only to materials that satisfy BS 6920, the standard for the suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of the water. The tests look at exactly the failure modes listed above: odour and flavour, appearance, the growth of aquatic micro-organisms, cytotoxicity and the extraction of metals.
• Approved products and materials are listed in the free online approvals directory, searchable by approval number, manufacturer or product type, so a part can be verified before it is fitted even when the packaging has gone in the skip.

Approval matters because regulation 4 needs evidence. A marked, listed or certificated fitting is your proof that the part in your hand meets the appropriate quality and standard — and it is your answer when a water undertaker's inspector or your supervisor asks what you fitted.

What to Check Before You Fit It

House Connections and Self-Lay

On new connections and self-lay projects the bar is explicit: materials as well as workmanship must meet the water undertaker's requirements. A Self-Lay Organisation laying its own mains and service pipes is still connecting to an undertaker's supply, so the same standards of approved pipe, fittings and jointing apply, and the undertaker will check both what was used and how it was used.

Site Scenario: The Sunday Emergency Repair

A Sunday call-out: a burst service pipe, and the only merchant open is a trade counter. There are two repair couplings on the shelf. One is cheap, unbranded and carries no markings at all. The other costs a few pounds more and carries a BS EN marking and an approval number you could check in the directory. The temptation is to grab the cheap one — it is an emergency, and it fits. The professional choice is the approved coupling. The unmarked one may leach, taint, support biofilm or simply fail again, and the moment it goes onto a wholesome-water supply the installation breaches regulation 4. Emergencies never justify unapproved materials.

Common Traps

• "If it fits, it's fine." Physical fit says nothing about water quality. A perfectly watertight joint can still leach, taint and feed biofilm.
• "Approval only matters for big jobs." Regulation 4 applies to every water fitting, including the washer in a tap repair.
• "Lubricant is lubricant." Generic oils and greases can dissolve into the water and nourish bacteria; only products declared suitable for wholesome-water fittings belong on the joint.