Guide to: DWI regulation 31

What is DWI regulation 31?

The Drinking Water Inspectorate (DWI) is an independent body which ensures water companies in England and Wales supply drinking water that meets acceptable quality standards. As repair and refurbishment specialists to the water industry, we operate under DWI regulation 31 to ensure the work we carry out doesn’t negatively impact drinking water quality.

What does the DWI do?


The DWI regulates water companies to ensure the drinking water they supply meets strict quality standards based on World Health Organisation guidelines.

Water authorities are required to provide daily samples of their drinking water, which are regularly tested by the DWI in its independant laboratories.

The DWI is also responsible for inspecting other aspects of water operations in the supply chain to ensure that our water is safe to drink at all times.

Regulation 31 of The Water Supply (Water Quality) Regulations 2016 implements Article 10 of the Council of the European Union Drinking Water Directive (DWD) in England and Wales for “all chemicals and construction products used by water undertakers, from the source of the water, up to the point of delivery to the consumer’s building”.

It sets out how to regulate any construction products and materials used in systems to make sure they don’t negatively impact water quality or customer safety.

Article 10 of the DWD states that:

Quality assurance of treatment, equipment and materials
Member States shall take all measures necessary to ensure that no substances or materials for new installations used in the preparation or distribution of water intended for human consumption or impurities associated with such substances or materials for new installations remain in water intended for human consumption in concentrations higher than is necessary for the purpose of their use and do not, either directly or indirectly, reduce the protection of human health provided for in this Directive; the interpretative document and technical specifications pursuant to Article 3 and Article 4 (1) of Council Directive 89/106/EEC of 21 December 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to construction products (1) shall respect the requirements of this Directive.

Our DWI work

As specialist contractors working with water authorities including Anglian Water and United Utilities, we use a number of DWI-approved products, including Sika and Flexcrete.

Are you looking for a specialist water industry contractor? Get in touch.