16 regional water companies supply drinking water across England and Wales, each in its own supply area as the water industry's supply-area boundaries draw it, and the quality of that water is regulated by the Drinking Water Inspectorate in England and Wales, per Water Company Boundaries (UC2) (19 September 2026, read 20 September 2026).
Source: Water Company Boundaries (UC2) — dated 19 September 2026, read 20 September 2026Water company boundaries © Water UK, licensed under CC BY 4.0
Drinking Water Inspectorate (DWI) enforces the UK drinking water quality regulations in England and Wales. Figures it classifies or regulates on this page cover England and Wales only.
Who supplies your water is not who bills you, or where you live
Water supply in the United Kingdom is appointed company by company, and the appointed areas do not follow county, city or postcode boundaries. Two neighbours can be supplied by different companies, and a company can supply water in one area and water and sewerage in another.
That is why this index exists, and why every company below links to what this site holds about it rather than to a summary written here. Restrictions, hardness and quality are all set or measured per company, so the company is the unit almost every question resolves to.
What this list is, and what it is not
The companies listed are the ones the water industry's own published supply-area layer names as regional appointees, plus the single public undertaker for each of the two nations that layer does not cover. Site-scale appointments inside somebody else's region are not listed: they are not the company a page about a supply area is about.
No row here states whether a restriction is in force. A restriction can start or end between updates of this list, so each company's status is kept on its own status page, or on the national tracker where it has none, and those pages are re-read whenever a new reading is published.
Every supplier, and what we hold on it
Supply areas: Water Company Boundaries (UC2) — dated 19 September 2026, read 20 September 2026Water company boundaries © Water UK, licensed under CC BY 4.0