- Drinking Water 2025 – Summary of the Chief Inspector’s report for drinking water in England
- Foreword
- Water supplies and testing
- Compliance with water quality standards
- Learning from microbiological failures
- Learning from turbidity failures
- Learning from chemical, taste and odour failures
- Learning from pesticide failures
- Asset health and service reservoir integrity
- Consumer contacts
- Drinking water quality events
- Water safety planning and risk assessment
- Perfluoroalkyl and polyfluoroalkyl substances (PFAS)
- Audit programme completed by the Inspectorate
- Air valve audits
- Enforcement, transformation and recommendations
- Materials in contact with drinking water (regulation 31)
- Security and Emergency Measures Direction - SEMD
- Network and Information Systems - NIS
- Research publications
- Whistleblowers
- Working with stakeholders
- Annex A – Number of tests carried out by companies
- Annex B – Compliance with standards
- Annex C – Compliance failures and events
Materials in contact with drinking water (regulation 31)
Regulation 31 prohibits a water company from applying any substance or product to, or introduce any substance or product into, water which may impact drinking water quality. This covers all chemicals, construction and treatment products used by water undertakers, from the source of the water, up to the point of delivery to the consumer’s building. This is a critical duty because materials can taint water by taste, odour or by leaching of harmful substances. The regulation sets out how approvals can be given to construction and treatment products and materials that do not prejudice water quality and ultimately consumer safety.
During 2025, the Inspectorate continued to receive and process applications for approval of products in contact with drinking water (under regulation 31). During this period a total of 545 enquiries were completed by the team. The volume of applications received was:
Figure 60 – Number of R31 applications
The Inspectorate has continued working with IT partners to further develop the regulation 31 portal for product approvals which has been well received overall. The new system replaced the previously used manual application forms with online, interactive application forms that will guide applicants in providing all the necessary information for an approval, product change or re-approval to be considered. The online process will have the benefit of meeting accessibility standards, allowing applicants to see what stage their applications have reached and making them available to more people with the next phase of the project delivering and end to end process.
In August 2025 we published a letter (DWI Ref: R31-06/2025) launching the new online interactive List of Approved Products. This has transformed from a monthly, published PDF document to an interactive, searchable website which is updated in real-time, something long requested by the industry and applicants. This has effectively become a live, online catalogue of approved products and can be found at: List of Approved Products for use in Public Water Supply in the United Kingdom – Drinking Water Inspectorate.
Identification of poor product stewardship continued throughout 2025 with a number of approved products being revoked from the Secretary of States List of Approved Products with immediate effect. All issues identified were as a result of unauthorised changes being made to a product. Where even the smallest unauthorised change has been made to a product formulation, material or component, the effect may lead to issues with unacceptable changes to water quality or a risk to public health. It is therefore imperative that all changes to formulation are approved prior to being implemented and supplied.
Where manufacturers have applied for changes to approved products, these will have been reviewed and where necessary testing undertaken prior to being accepted. This ensures that there are no issues with the products when in use.
The table below lists the products revoked and the associated letters issued during 2025 with some products completely revoked and requiring a full re-application and other products having conditions of use imposed.
Regarding Arlington 1000 Litre Bag-in-Box Combo Liner, conditions of use were applied to the product rather than a full revocation to allow water for domestic use to be available during the summer where many water companies were experiencing prolonged dry weather. This is an example of the pragmatic approach taken by the team during the year.
| Date | Action | Product / Manufacturer | Reference number | Details / Conditions |
|---|---|---|---|---|
| Jan 25 | Revocation of product approval | GF ABS Pressure Pipe / George Fischer | R31-01/2025 | |
| Jan 25 | Revocation of product approval | 8040-SBNF-DWI Membrane Elements / Mann+Hummel Water and Fluid Solutions | R31-02/2025 | |
| Apr 25 | Revocation of product approval | PE100 High Performance Black Pipe / Radius Systems Ltd. | R31-03/2025 | |
| Aug 25 | Update to requirements for approval | Arlington 1000 Litre Bag-in-Box Combo Liner | R31-04/2025 | This product cannot be used for drinking or cooking purposes. Changes take effect from 06/08/2025. |
| Aug 25 | Update to requirements for approval | Amazon SupaSpun II Cartridge Filters and Amazon SupaGard Cartridge Filters | R31-05/2025 | Products supplied before 06/08/2025 shall be quarantined and cannot be installed. Stocks of already purchased product must be quarantined and clearly labelled as not to be used until further notice. |
| Oct 25 | Removal of recognised grade status | Eurokote® 468 Thixo & Eurokote® 468 Thixo 500 Brun Rouge | R31-08/2025 | Issue with naming of various products resolved. |
Issues with some of the revoked products have since been resolved and these products have returned to the List of Approved Products. It should be noted that the name of the product and reference number are likely to have changed. Others will be undergoing full review and additional testing to verify whether they can be approved.
The Inspectorate does not take the decision to revoke products or prohibit the use of products lightly however, where the stringent requirements to maintain the product approvals are not met, and constitutes a potential concern to public health then the decision to revoke the product can be taken. Use of an unapproved product is an offence and can be prosecuted under regulation 33.
In addition, several approval holders either made late applications or omitted to apply for product reapprovals which resulted in a delay in reapprovals being assessed. This resulted in an increase in expired products with manufacturers having to undertake the entire process of product approval from the beginning.
In December 2025, manufacturers were informed via letter, DWI Ref: R31-10/2025, that there will be a requirement for all recognised grades currently contained in Annex 3 of the List of approved Products, to go through the approval process with the requirement that they apply for this approval by end of June 2026. This will allow us to keep an updated list of recognised grade products and their current formulations.
There has been significant work undertaken by the Inspectorate to secure testing facilities for BS6920 and full regulation 31 testing throughout the year with five laboratories being added to the list of designated laboratories for BS6920 testing in February 2025. A laboratory was recently designated to undertake full regulation 31 testing capability, and we continue to work towards increasing this capacity throughout 2026. We are also collaborating with the water industry to resolve the issue, and this work continues. Laboratories are required to demonstrate and evidence compliance with the relevant standards and protocols to become designated for regulation 31 testing.
Following members of the regulation 31 team presenting on the challenges of regulation 31 testing and discussion at Northumbrian Water’s Innovation Festival in July 2025, the team has also collaborated with Ofwat’s Innovation Enablers team to publish an expression of interest for progressing further laboratory testing which is due for publication in Q1 of 2026. This work seeks to provide a pathway for laboratories to undertake full regulation 31 testing requirements.