London and Thames Valley
EA rated Thames Water one star in the 2024 environmental performance assessment. Ofwat says Thames is in turnaround oversight and needs material improvements including leakage and internal sewer flooding.
Regional watch
Find the company, then check the right data.
This is a map-style starting point for England and Wales. It is not a boundary map for billing. Use the supplier finder or your bill to confirm the exact water and wastewater companies for an address.
Map guide
Tap a region idea, then use the official data source.
Some areas have separate water-only and wastewater companies. Pollution and sewerage performance usually sits with the wastewater company.
United Utilities
North West Northumbrian
North East Yorkshire
Yorkshire Severn Trent
Midlands Dwr Cymru
Wales Anglian
East Thames
London area Southern
South East South West
South West Wessex
South West
North West Northumbrian
North East Yorkshire
Yorkshire Severn Trent
Midlands Dwr Cymru
Wales Anglian
East Thames
London area Southern
South East South West
South West Wessex
South West
What the colours mean
Use this as a visual index, not a verdict. Company performance changes each reporting year.
Find exact supplierCompany watch cards
What to check by company area.
These cards combine current official source notes. They are deliberately cautious: they show where to look, not a final judgement on any household bill.
South East coast
EA rated Southern Water two stars in 2024. Ofwat notes improvements in pollution and leakage from 2023-24 levels, but says long duration interruptions are particularly concerning.
South West
EA rated South West Water two stars and said it performed worst for total sewerage pollution incidents per 10,000km sewer in 2024. CCW also rated South West Water poor on complaint volume and handling metrics.
Yorkshire
EA rated Yorkshire Water two stars in 2024. CCW rated Yorkshire Water poor on complaint volume and handling metrics. Ofwat announced a GBP 40m wastewater enforcement package.
North West
EA rated United Utilities two stars in 2024. Ofwat's performance report shows per-capita consumption improved over 2020-25, but EA listed United Utilities among companies significantly below target for total sewerage pollution incidents.
East of England
EA rated Anglian Water two stars in 2024. Ofwat says Anglian met its adjusted per-capita consumption commitment in 2024-25 but needs improvement on pollution incidents.
Wessex region
EA rated Wessex Water two stars in 2024. Ofwat says Wessex has been strong on treatment works compliance and customer satisfaction, while leakage and pollution incidents still need improvement.
Midlands and parts of Wales
EA rated Severn Trent four stars in 2024 and said it was the only company to consistently achieve four stars in the last six years. Ofwat still expects reduction in pollution incidents.
Most of Wales
Ofwat says Dwr Cymru needs material improvement in several areas, including supply interruptions and leakage. Ofwat's Dwr Cymru decision covered misreported leakage and per-capita consumption data and customer redress.
North East and Mid Wales
Ofwat says Hafren Dyfrdwy has shown consistently strong performance in several areas, including pollution incidents and drinking-water quality, but needs to improve internal sewer flooding.
North East and Essex/Suffolk water services
EA rated Northumbrian two stars in 2024. Ofwat says it has strong performance in multiple areas and ended the period as a top performer in water supply interruptions, but pollution incidents need improvement.
Affinity, Portsmouth, South East, South Staffs, SES, Bristol
Water-only companies do not operate sewerage for those areas. Check drinking-water, interruptions, leakage, bills, and arrears with the water-only company, then check wastewater issues with the separate sewerage company.
What to inspect
Use these official datasets for each area.
Leakage
Use Ofwat's Water Company Performance Report and Discover Water to compare leakage trends and company targets.
Pollution
Use the Environment Agency EPA for England, NRW reports for Wales, and Ofwat wastewater investigation updates.
Drinking water
Use DWI annual reports and the DWI problem route for taste, odour, colour, and water-quality concerns.
Complaints
Use CCW complaint handling reports and company complaint performance pages for household complaint patterns.
Regional watch source links
Water UK supplier finder
Ofwat company contact map
Discover Water dashboard
Ofwat performance 2024-25
EA environmental performance 2024
NRW environmental reports
Last checked: 1 June 2026. The map is a guide, not a billing-boundary source.