UK & Ireland Water Hardness
How hard is the water coming out of your tap?
Look up the hardness of your water by city, town, region and postcode, taken from your water supplier's own published reports or databases. Use it to choose the right water softener and set up your appliances properly.
Charts available for
The basics
What is hard water?
Hard water carries dissolved minerals, mainly calcium and magnesium, picked up as rain soaks through chalk and limestone on its way to reservoirs and boreholes. The more of these minerals your water holds, the harder it is.
Hardness is safe to drink, but it leaves limescale wherever water is heated or left to dry: inside kettles and boilers, on shower screens and taps, and in the elements of washing machines and dishwashers.
Why it matters
Know your water hardness
Water hardness in the UK and Ireland depends on the geology beneath your supply, so it can differ between neighbouring towns. Knowing your number helps you:
- size a water softener correctly for your home
- set the water hardness level on your dishwasher or washing machine and other appliances
- protect your boiler, kettle and shower from limescale build-up
Reading the charts
One value, five units
Appliance manuals and softener makers use different units, so every chart shows your hardness in all of them.
- mg/l
- Milligrams per litre
- gpg
- Grains per US gallon
- °Clark
- English degrees
- °dH
- German degrees
- °fH
- French degrees
Who Has the Hardest Water?
See the top ten water supply zones with the hardest water in each nation, ranked using the water suppliers' own primary data. Each list names the city, town and county or council area served, so you can see whether your area is among the hardest.