Rankings based on nitrates, trihalomethanes, lead levels and PFAS enforcement notices across every supply zone in England, Wales and Scotland.
See where your zone sits in the rankings
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How we score: Each zone starts at 100/100.
Nitrate >25 mg/L: −10 · >40: −25.
THMs >50 µg/L: −10 · >80: −25.
Lead >5 µg/L: −10 · >10: −25.
Active PFAS programme: −15.
Hardness >300 or <50 mg/L: −5.
Score shown as X/10. Zones with no reported data score 10/10 by default — check your postcode for full details.
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Zones with the best combination of low nitrates, THMs, lead, and no PFAS notices.
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Zone
Company
Score
Nitrate
THMs
Lead max
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Zones with the most elevated contaminant levels. All water is still safe to drink and meets legal standards.
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Zone
Company
Score
Nitrate
THMs
Lead max
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Average score across all zones for each water company.