Compare tap water hardness in 10 cities in South East England, England. Average: 26.9°fH (Average quality).
In South East England, tap water hardness averages 26.9°fH, corresponding to hard water. The softest water is found in Tunbridge Wells (9.7°fH, score 9/10) and the hardest in Harrow (36.1°fH, score 3/10). The England average in our dataset is 18.1°fH. All 10 cities have water compliant with DWI regulations (Water Supply (Water Quality) Regulations 2018).
The average tap water hardness in South East England is 26.9°fH, corresponding to hard water. Among the 10 cities covered, the softest water is found in Tunbridge Wells (9.7°fH) and the hardest in Harrow (36.1°fH). The England average in our dataset is 18.1°fH.
Yes. Tap water in South East England is regulated by the Drinking Water Inspectorate (DWI) under the Water Supply (Water Quality) Regulations 2018. Water hardness of 26.9°fH does not affect safety; it only influences appliance maintenance and taste. All 10 cities in our database have compliant water.
With an average of 26.9°fH, a water softener or anti-scale filter is a worthwhile investment in South East England. Limescale significantly shortens the lifespan of boilers, washing machines and kettles. A softener is particularly recommended in cities above 30°fH such as Harrow (36.1°fH).
Water in South East England is supplied by South East Water, Southern Water, Thames Water, Affinity Water. Data in our database comes from official zone-level analyses published by these utilities (2025).
All 10 cities in South East England with their hardness values are listed on this page. Click on any city name to get full details: quality index, DWI compliance, impact on appliances and personalised recommendations.
Data: South East Water, Southern Water, Thames Water, Affinity Water official zone-level hardness reports (2025). Readings verified via DWI drinking water quality database.