Annual Report
UK Water Quality Report 2026
According to TapWater.uk's analysis of 2,245 UK postcode districts, the national average water quality score is 9.0/10 in 2026. All UK tap water meets legal safety standards — scores reflect levels relative to WHO guidelines.
9.0/10
National average
2,245
Postcodes analysed
26+
Contaminants monitored
29
PFAS detections
Best & worst cities
The UK cities with the highest and lowest average water quality scores, based on postcode-level testing data.
Top 5 — Best water quality
Most common contaminants
The 10 most frequently flagged contaminants across all UK postcode districts monitored. A contaminant is "flagged" when levels exceed WHO guidelines, even if within UK legal limits.
Flagged means the measured value exceeds the WHO guideline or UK regulatory limit for that parameter. A postcode is counted once per contaminant regardless of how many samples were taken.
PFAS: the emerging threat
PFAS ("forever chemicals") were detected in 29 postcode districts, representing 1.3% of all areas monitored. These synthetic compounds persist indefinitely in the environment and accumulate in the human body. The UK currently has no legal limit for PFAS in drinking water, though the Drinking Water Inspectorate is actively reviewing the evidence.
PFAS detections are concentrated in industrial areas and near military bases where firefighting foams have been used. Reverse osmosis and activated carbon filters can reduce PFAS levels by 90% or more.
Water supplier performance
18 UK water companies ranked by average safety score across all postcodes in their service area.
Only companies serving 2 or more postcode districts are shown. Score is the unweighted average across all postcodes in the supplier's coverage area.
Hard water map
56.2% of UK postcode districts with hardness data have water above 200 mg/L CaCO3 — classified as "hard" or "very hard." That's 913 out of 1,624 areas tested.
Hard water is not a health risk, but it increases energy bills, shortens appliance lifespans, and causes limescale buildup. A water softener can save an estimated £200+/year in a hard water area.
Regional headlines
The same dataset, cut by region: ready-made local angles, free to cite with attribution to TapWater.uk.
Writing about this? The datasets are free.
Five ready-made datasets as CSV, plus citation text and an embeddable postcode widget, all free to use with attribution.
Methodology
Each UK postcode district receives a safety score from 0 to 10 based on measured contaminant levels against two benchmarks: UK legal limits (set by the Drinking Water Inspectorate) and WHO advisory guidelines. Scores are computed daily from the latest available monitoring data.
City, supplier, and regional scores are unweighted averages across all postcode districts with valid data in the most recent 3 years. PFAS detections are flagged separately because the UK has no legal limit for PFAS in drinking water. A lower score does not mean water is unsafe — all UK tap water meets regulatory standards.
Data sources
Environment Agency Water Quality Archive
Environmental monitoring data for rivers, groundwater, and abstraction points across England. Open Government Licence v3.
Drinking Water Inspectorate (DWI)
Regulatory compliance data for all public water supplies in England and Wales.
Stream Water Data Portal
Real-time drinking water test results from UK water companies, including treatment works output and distribution network sampling.
Check your water quality
Enter your postcode to see a detailed water quality report for your area, including contaminant levels, PFAS status, and supplier information.