16 regional water companies supply the tap water in England and Wales, and the quality of that water is regulated by the Drinking Water Inspectorate in England and Wales, per the water industry's own Water Company Boundaries layer (UC2) (19 September 2026, read 20 September 2026).
Source: the water industry's own Water Company Boundaries layer (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.
What this page can tell you, and what it cannot
This page is an index of what this site holds about the water supplied to towns in this country. What it holds is the monitoring record each water company publishes for itself: sample results, in datasets the company puts out and anybody can open.
What it does not hold is a judgement. Nothing in this section compares one of those results against a standard, so no page here says whether a supply meets one. Where a reader wants that judgement, it belongs to the regulator, whose own pages are linked below.
Who decides this, and who publishes what
Water here is supplied by companies, each responsible for its own area, and overseen by a regulator that sets the standards and enforces them. The regulator publishes the rules; the companies publish the measurements. There is no single national dataset behind either.
So a figure on these pages is a water company's own, quoted with the document it came from and the day that document was read. Where a company publishes nothing that can be read in bulk, the page says that instead of filling the space.
Why a town gets a page here, and why most do not
A town earns a page when somebody measurably searches about its water and the national postcode directory, placed in the water companies' own supply-area boundaries, shows one company serving most of it. Each is a measurement rather than an editorial choice, and the table below prints which one failed.
A town's page names every company serving part of it and how many of its postcodes each one serves, because supply areas are not administrative areas. Where the company serving most of a town is one this programme holds no drinking-water data for at all, the town gets no page, and the row says why in that company's own terms.
What a row with no page means, and what it does not
A town with no page is not a town whose water went unmeasured, and it is certainly not a town where nothing was found. What is missing is a published record this site can read and attribute correctly.
Nothing here is estimated to fill that gap, and no record is borrowed from a neighbouring area or from another company. Where we hold nothing, the row says we hold nothing, and prints the evidence for saying it.
What DWI sets, and what we hold of it
Drinking Water Inspectorate publishes the UK drinking water quality regulations, and this programme holds none of those values as data: 0 determinands have been reviewed into its vocabulary for this country, and a reviewed entry carries no field for a limit in any case. So nothing on this page is compared against a standard, and no row below is a verdict — the published monitoring record is what a company measured, not whether it passed.
Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026
What we hold today
Counted from the table below: 8 towns whose water company publishes a record we read in full carry a published figure. The table covers 12 post towns with measured demand and a postcode count, which is every one this country holds, and they fall into 4 groups.
- Its water company's record, read in full: 8
- Its water company's record, read as a bounded sample: 0
- No record we can read for this town's water company: 4
- Outside every source this programme holds: 0
Every one of the post towns with measured demand and a postcode count, and what we hold for it
| post towns with measured demand and a postcode count | What we hold | Source |
|---|---|---|
| Birmingham | Counted dataset by dataset, never added together — 5 drinking-water-quality datasets, published by Severn Trent Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Bournemouth | Counted dataset by dataset, never added together — 4 drinking-water-quality datasets, published by South West Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Bristol | South West Water publishes the Bristol Water area on the water industry's shared data portal as a region of its own, in 3 annual performance reports, and none of its 4 drinking-water-quality datasets there is published for that area (read 20 September 2026). Their company-wide sample counts are therefore not printed here as Bristol's. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Cambridge | Counted dataset by dataset, never added together — 2 drinking-water-quality datasets, published by South Staffordshire Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Leeds | Counted dataset by dataset, never added together — 1 drinking-water-quality datasets, published by Yorkshire Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| London | Thames Water publishes no drinking-water-quality dataset on the industry ArcGIS organisation this site reads (read 20 September 2026), so this site holds no compliance figure for its supply. That is an absence of published data, not a clean record. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Manchester | Counted dataset by dataset, never added together — 2 drinking-water-quality datasets, published by United Utilities and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Nottingham | Counted dataset by dataset, never added together — 5 drinking-water-quality datasets, published by Severn Trent Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Sheffield | Counted dataset by dataset, never added together — 1 drinking-water-quality datasets, published by Yorkshire Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Southampton | Counted dataset by dataset, never added together — 10 drinking-water-quality datasets, published by Southern Water and read in full. Their row counts are printed separately on the town's own page: a supplier's datasets cover different supply regions, so one total would describe an area no dataset covers. | Source: the Stream ArcGIS organisation — every service it publishes, enumerated — dated 20 September 2026, read 20 September 2026 |
| Edinburgh | Edinburgh has 60/mo of measured demand for its water (hardness searches; none was measured for its safety) and no page: it is supplied by Scottish Water. We hold no drinking-water data for Scotland. Every source this site reads — the water companies' published quality results, their supply-zone hardness reports, the regulator's supply-zone notices and the Environment Agency's storm-overflow return — covers England and Wales only. Scotland's drinking water is regulated separately, by the Drinking Water Quality Regulator for Scotland. | Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0 |
| Glasgow | Glasgow has 30/mo of measured demand for its water (hardness searches; none was measured for its safety) and no page: it is supplied by Scottish Water. We hold no drinking-water data for Scotland. Every source this site reads — the water companies' published quality results, their supply-zone hardness reports, the regulator's supply-zone notices and the Environment Agency's storm-overflow return — covers England and Wales only. Scotland's drinking water is regulated separately, by the Drinking Water Quality Regulator for Scotland. | Source: ONS Postcode Directory (May 2026), each postcode placed in the water companies' supply-area boundaries — read 26 September 2026Contains OS data © Crown copyright and database right 2026Contains Royal Mail data © Royal Mail copyright and database right 2026Source: Office for National Statistics licensed under the Open Government Licence v.3.0Water company boundaries © Water UK, licensed under CC BY 4.0 |
Look up your own area
- Is tap water in Birmingham safe to drink?
- Is tap water in Bournemouth safe to drink?
- Is tap water in Bristol safe to drink?
- Is tap water in Cambridge safe to drink?
- Is tap water in Leeds safe to drink?
- Is tap water in London safe to drink?
- Is tap water in Manchester safe to drink?
- Is tap water in Nottingham safe to drink?
- Is tap water in Sheffield safe to drink?
- Is tap water in Southampton safe to drink?
- Every water company, and what we hold for it