Portsmouth Water Tap Water Quality

Portsmouth Water supplies Hampshire with drinking water drawn from chalk aquifers of the South Downs in Hampshire, with boreholes at Havant and Bedhampton.

Portsmouth Water is one of the UK's smallest water companies, serving Hampshire including Portsmouth, Havant, and Chichester. The entire supply is drawn from the South Downs chalk aquifer — this produces consistently hard water at 210–250 mg/L CaCO₃ throughout the supply area. As a chalk-only supply, the water is very consistent in quality. Nitrate levels are moderate; the chalk aquifer provides natural filtration. The company maintains a clean compliance record and was among the first to introduce active PFAS monitoring in response to near-airport abstraction sources.

Typical water profile

With typical hardness of approximately 230 mg/L CaCO₃, water in the Portsmouth Water supply area is classified as hard. This means significant limescale buildup on kettles, showerheads, and heating elements over time. A water softener or quality filter jug is a worthwhile investment for most households in this area.

Notable: Consistently hard chalk water (~230 mg/L). Very consistent quality — chalk-only supply. Active PFAS programme near airport sources under DWI enforcement.

Is Portsmouth Water water safe to drink?

Yes. All treated water supplied by Portsmouth Water meets the UK Drinking Water Regulations. The Drinking Water Inspectorate (DWI) audits every water company annually — Portsmouth Water serves 0.7 million customers across 15 supply zones. Each zone is tested thousands of times per year and results are published in the annual compliance report.

However, water quality varies significantly between zones within the Portsmouth Water supply area. Your specific zone may have different hardness, nitrate, or THM levels from your neighbour in a different zone. That's why it's worth checking your exact postcode above.

How to check your Portsmouth Water zone

Enter your postcode in the box above to see zone-specific data for your address — including hardness, nitrates, lead, chlorine, fluoride, and THMs — drawn directly from Portsmouth Water's most recent annual compliance report.