19 postcode districts testedWater quality in South East England
According to TapWater.uk's analysis, South East England scores 8.9/10 for drinking water quality in 2026, based on data from 19 postcode districts. Water quality in Kent, Sussex, Surrey, Hampshire and surrounding areas. Supplied by Southern Water, South East Water, and Portsmouth Water.
8.9 / 10
19 areas tested · 2 suppliers · PFAS in 1
Tap water in South East England has an average safety score of 8.9 out of 10 based on testing across 19 postcode districts. Water is supplied by Southern Water, Portsmouth Water. PFAS (forever chemicals) have been detected in 1 areas. The overall water quality is good. Data is sourced from the Environment Agency and water company testing via the Stream Water Data Portal.
Cities in South East England
Average water quality score by city.
276mg of limescale minerals in every litre, on average across South East England
South East England water is very hard
Hard starts at 180 mg/L, very hard at 250. Hardness varies by area; check your own postcode for the reading where you live.
Softener quotes in South East England
At 276 mg/L a softener protects the boiler, kettle and taps. Tell us your postcode and we will pass your request to installers who cover it. Free, no obligation.
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River health around South East England
1 of the 10 rivers and waters that South East England drains into is rated good or high by the Environment Agency. All of them fail the chemical test, as every river in England does, because of long-lasting pollutants such as mercury and PFOS. This describes the rivers, not your tap water.
| River or water | Ecological health | Postcode districts |
|---|---|---|
| Sussex | Moderate | BN1, BN2, BN3, BN41 |
| Southampton Water | Moderate | SO14, SO17, SO19 |
| Portsmouth Harbour | Moderate | PO1, PO2 |
| Solent | Moderate | PO4, PO5 |
| Tanner's Brook | Moderate | SO15, SO16 |
| Horton Heath Stream | Moderate | SO30 |
| Langstone Harbour | Moderate | PO3 |
| Monks Brook | Moderate | SO53 |
| Potwell Trib | Moderate | PO6 |
| Itchen | Good | SO18, SO50 |
Environment Agency classification, 2025. River health across England
Questions about South East England water
Is tap water safe in South East England?
Based on our analysis of 19 postcode districts in South East England, the average water quality score is 8.9/10, which is safe. Water is supplied by Southern Water, Portsmouth Water.
Which area has the best water in South East England?
SO18 (Southampton) has the highest water quality score in South East England at 9.4/10.
Which area has the worst water in South East England?
SO53 (Eastleigh) has the lowest water quality score in South East England at 8.3/10. Check the postcode page for details on specific contaminants.
Is South East England water hard or soft?
Water in South East England has an average hardness of 276 mg/L CaCO₃, which is classified as very hard. Hardness varies by area — check your postcode for exact levels.
Who supplies water in South East England?
Water in South East England is supplied by Southern Water, Portsmouth Water.
Is there PFAS in South East England water?
PFAS (forever chemicals) have been detected in 1 out of 19 postcode districts tested in South East England. The UK currently has no legal limit for PFAS in drinking water.
Data sourced from the Environment Agency Water Quality Archive and water company testing via the Stream Water Data Portal. See our methodology for how scores are calculated. Reviewed by the TapWater.uk research team.