Products that can be approved

Only products that are used by or will be used by drinking water suppliers in the United Kingdom – from the source, through treatment, to the point of supply to consumers’ premises – can be approved under the relevant regulations.

What types of products can be approved?

  • Treatment chemicals: Flocculants and coagulants, disinfectants, not covered by BS EN (products for use in building water systems cannot be considered)
  • Treatment process products: Adsorbents, ion exchange resins, membranes, on-site chlorine generators, filter media, vessels and containers, electrodialysis water treatment units, pressure vessels, products used for the physical treatment of water.
  • Pipes and associated components including coatings: Polyethylene (PE) (including barrier and laminated), polyvinylchloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene terephthalate (PET), glass reinforced plastic (GRP), stainless steel, and lined metallic pipes.
  • Site applied and in-situ coatings: coatings based on epoxy or polyurethane resins.
  • Repair materials
  • Water retaining structures
  • Covers and linings
  • Underdrains
  • Products for emergency use with public water supplies

The current list of approved products can be found on our website

Some products are covered under relevant European standards and cannot be considered for approval:

  • Chemical products used for treatment of water, based solely upon a treatment chemical covered by a relevant BS EN standard
  • Inorganic supporting and filtering materials used for treatment of water intended for human consumption, covered by relevant BS EN standards

Building water systems

Products used in customers’ premises, in public buildings are covered by different approval requirements and regulations The Water Supply (Water Fittings) Regulations 1999 (,
and cannot be approved under Regulation 31 of the Water Supply (Water Quality) Regulations.

For a comprehensive explanation, including the role of the Water Regulations Advisory Scheme (WRAS), see Annex 1 below.

Swimming Pool water treatment

Although a voluntary non-regulatory approval scheme for swimming pool chemicals was operated by the former Department of the Environment, Transport and the Regions (DETR) until 1999, this scheme was abandoned for a number of reasons, including:

  • DETR never had operational or policy responsibilities for swimming pools and no other Department wanted to accept this responsibility
  • Chemical suppliers were reluctant to agree to an audit scheme to check the ongoing quality of the products approved under the voluntary scheme
  • There were concerns about potential product liability issues, if someone suffered ill-health as a result of using an approved product

DETR sought to replace the voluntary scheme by a programme for the development of European Standards for swimming pool chemicals. Details of these standards are available from British Standards Institution –

DWI and DEFRA do not publish lists of swimming pool treatment chemicals.

GENERAL NOTE: the Drinking Water Inspectorate in unable to comment on:

  • the suitability for use within building water systems or in the treatment of swimming pool waters, of any product approved under Regulation 31 of the Water Supply (Water quality) Regulations, including their fitness for purpose
  • the use of any other treatment chemical, product/device or process within building water systems or in the treatment of swimming pool waters

All such enquiries should be made directly to:

  1. Water Regs UK Limited for building water systems
  2. PWTAG | The home of the Pool Water Treatment Advisory Group (PWTAG) for swimming pool waters

Annex 1 – What is the relationship between the approval schemes run by WRAS and the DWI?

The Water Regulations Advisory Scheme (WRAS)

This Scheme is operated behalf of the UK water industry by WRAS Ltd. The Scheme approves water fittings and materials, for use within consumers’ premises, to the requirements of the Water Supply (Water Fittings) Regulations 1999. For most non-metallic materials test methods and acceptance criteria for potential effects on water quality are specified in BS 6920[1].These tests include odour and flavour, appearance, growth of aquatic microorganisms, leaching of metals, and cytotoxicity. The scheme normally only accepts test reports from laboratories that have been accredited (under EN ISO/IEC 17025) for BS 6920 testing by the United Kingdom Accreditation Service (UKAS).

Materials which meet the full test requirements of BS 6920:1 can be listed in the materials section of the Water Regulations Approval Scheme Ltd – Approvals Directory ( . In many cases WRAS will accept the use of listed materials in fittings without the need for any further testing, although mechanical testing of the fitting may be required.

WRAS is concerned primarily with products used in BUILDINGS (CONSUMERS’ PREMISES) – the requirements of the Water Supply (Water Fittings) Regulations 1999 apply.

[1] BS 6920 – Suitability of non-metallic products for use in contact with water intended for human consumption with regard to their effect on the quality of water

Regulation 31 Approval Scheme

The Drinking Water Inspectorate (DWI) operates the approval system for products used by UK water suppliers under the requirements of the relevant regulations on behalf of the national authorities . DWI can accept applications for approval of products used both before and at the treatment works and in water distribution systems up to the point of delivery to premises. The only products considered for approval under Regulation 31 are those sold to water undertakers in the United Kingdom for use with water intended for human consumption.

When considering non-metallic products for approval under the relevant regulations, however, the DWI does take into account the results of BS 6920 testing undertaken as part of the approval process for products listed by WRAS. Where products have not been previously tested to BS 6920 and/or listed by WRAS, a normal requirements for approval will include satisfactory results in the BS 6920 tests – see Section 4.2 of our Advice Sheet 1 for further details.

Products recommended for approval under Regulation 31 are listed in the Approved & Considered Products – Drinking Water Inspectorate (

DWI does not approve any product for use with drinking water – [ link to FAQ2]

The DWI only considers products (treatment chemicals and construction products) used in the PUBLIC WATER SUPPLY, i.e. between the point of source of water and the point of supply to consumers’ premises.

Table of Comparison

The following table summarises the differences between WRAS approvals and those given under Regulation 31

Within buildings (WRAS)In drinking water supply
Building water systems – consumer’s premisesFrom source to consumer’s premises (including treatment works)
Individual materials
Final products, including pipes, fittings and assembled products etc
Treatment chemicals
Final products, including treatment plant, pipes, fittings and assembled products
Legal basis – the Water Supply (Water Fittings) Regulations 1999Legal basis – the relevant regulations
Testing to Parts 1 to 3 of BS 6920Testing to Parts 1 to 4 of BS 6920, plus additional tests specified on a case-by-case basis
Direct effects on water quality – odour and flavour, colour and turbidity, microbial growth, leaching of metalsDirect effects on water quality – odour and flavour, colour and turbidity, microbial growth, leaching of metals
Health risks, usually associated with organic compounds leaching from the product
Table to compare the differences between WRA approvals and those given under Regulation 31
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