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How hard or soft is my water?

How hard or soft your tap water is depends on your local geology and varies widely across the UK.


What makes water hard or soft?

'Hard' water is water with a lot of calcium in it. This doesn't affect drinking water quality.

Rainfall doesn't contain any calcium, but as the water flows over the land and filters through rocks, it dissolves minerals and becomes harder. The more calcium water contains, the harder it is and the less it contains, the softer the water is.

How hard your water is depends on local geology.

Check your water

Enter your postcode to check the hardness of your water and download your full water quality report.

Frequently asked questions about hard water

Here you can find answers to some frequently asked questions about water hardness.

Most of the water we supply is hard, as it comes from underground chalk aquifers with high levels of calcium.

We don't soften water before it reaches your taps – there's no UK or European standard for the hardness of drinking water.

  • Soft water contains less than 100mg of calcium carbonate per litre.
  • Moderately hard water contains between 100 and 200mg of calcium carbonate per litre.
  • Hard water contains between 200 and 300mg of calcium carbonate per litre.

Very hard water contains more than 300mg of calcium carbonate per litre.

Yes. Most water softeners work by adding sodium which can significantly raise the levels of sodium in your body. This can especially be harmful for premature babies and people on low-sodium diets. 

If you do wish to install a softener, it's very important to remember not to soften water that feeds into the kitchen tap that you use for cooking or drinking.

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