Drinking Water Inspectorate
Drinking water quality in England and Wales
The statutory regulator of drinking water quality in England and Wales. Publishes annual compliance data against the Water Supply (Water Quality) Regulations, zone-level test results, enforcement action, and investigations into water quality events.
Rights
- Licence
- Open Government Licence v3.0
- Commercial reuse
- Yes
- Redistribution
- Yes
- Derivative use
- Yes
- Attribution required
- YesContains public sector information licensed under the Open Government Licence v3.0.
- Terms last checked
- 23 August 2026
Access and coverage
- Publisher
- Drinking Water Inspectorate
- Website
- https://www.dwi.gov.uk/
- Geographic coverage
- England and Wales — water supply zone level
- Temporal coverage
- 1990 onwards
- Update frequency
- annual
- Formats
- csv, xlsx, pdf, html
- Bulk download
- Available
- Registration required
- No
- Cost to Hydrionis
- Free
- Domains
- quality, contaminant, chemistry, enforcement
Notes
DWI compliance is reported per supply zone, typically serving up to 100,000 people. That is the native geography (spec §7): a zone result cannot be attributed to an individual property, and Hydrionis presents it as zone-level throughout.