2026 Report
UK Water Quality Rankings
Based on 2,237 postcode districts tested. Last updated: 1 April 2026.
43
Cities ranked
16
Water companies
10
Regions
2,237
Areas tested
Best & worst cities
The cities with the highest and lowest average water quality scores in the UK.
Top 5 — Cleanest water
All cities ranked
43 cities, ranked by average water quality score. Click any city for a detailed breakdown.
Score is average across all postcode districts in each city. PFAS column shows number of postcode districts where forever chemicals were detected.
Water company leaderboard
16 water companies ranked by average safety score across all postcodes served.
Only companies serving 2 or more postcode districts are shown. Score is the unweighted average across all postcodes in the supplier's coverage area.
Regional comparison
10 regions ranked by average water quality score.
Wales
2 cities · 19 areas
/10
Yorkshire and the Humber
5 cities · 96 areas
/10
North East England
3 cities · 33 areas
/10
North West England
4 cities · 57 areas
/10
West Midlands
4 cities · 71 areas
/10
East Midlands
3 cities · 20 areas
/10
East of England
3 cities · 23 areas
/10
South West England
4 cities · 38 areas
/10
South East England
3 cities · 21 areas
/10
London
1 cities · 80 areas
/10
How these rankings work
Rankings are based on water quality monitoring data from the Environment Agency Water Quality Archive and water company testing via the Stream Water Data Portal. Each postcode district receives a safety score from 0–10 based on measured contaminant levels against UK legal limits and WHO guidelines. City, supplier, and regional scores are averages across all postcode districts with data.
A lower score does not mean water is unsafe — all UK tap water meets legal standards. Scores reflect how cleanly water performs relative to both mandatory UK limits and stricter WHO advisory guidelines. PFAS detections are flagged where detected, even though the UK has no legal limit for PFAS in drinking water.