UK hard-water map
Why your shower feels different by postcode.
Water hardness varies by geology and local supply zone. The map below is a practical guide for England and Wales, not a postcode-level test. Across east and south east England, chalk and limestone geology makes hard-water complaints especially common. For an exact reading, use your water company's postcode checker.
How to read it
Soft to moderately soft areas tend to create less visible limescale.
Mixed areas can vary strongly by supply zone.
Hard areas commonly see more scale around taps and shower fittings.
Very hard areas are where pressure, limescale and hair-rinse complaints are easiest to explain visually.
What hard water means in the shower
Limescale
Hard water causes scaling in hot water systems and appliances because calcium and magnesium deposits build up over time.
Less lather
The Drinking Water Inspectorate notes that hard water produces less lather from soap and washing products.
Local variation
Two nearby homes can have different readings, so a supplier postcode checker is the best final answer.
Sources: the Drinking Water Inspectorate explains hardness and provides a typical England and Wales map; Thames Water explains why its region is hard and publishes hardness categories in mg/l CaCO3.