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How hard your tap water is depending on your local area and varies widely across the UK. Check the hardness of your water by postcode and download your full water quality report.
Hard water is water with a lot of calcium in it. This doesn't affect drinking water quality. When rainwater falls it’s natural soft but as the water flows over the land and filters through rocks, it picks up dissolved minerals, like calcium, 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 and areas with lots of limestone or chalk have harder water, while places with granite or peat have softer water.
Enter your postcode to check the hardness of your water and download your full water quality report.
The quality of your water is monitored in accordance with a strict set of rules laid down in the Water Supply (Water Quality) Regulations 2000.
The Drinking Water Inspectorate is responsible for monitoring compliance with these regulations.
Every year, several hundred thousand samples are taken from our treatment works, underground service reservoirs and customers' taps.
Hard water is safe to drink, but it can cause problems by forming a harmless scum called limescale - you’ll no doubt have seen it at the bottom of your kettle, or even floating in your tea. Follow these tips to help you deal with hard water and protect your pipes and appliances.
To stop scum from forming, you should clean your appliances and taps regularly. You can do this with household cleaners or you can also try a mixture of bicarbonate of soda and white vinegar.
You can sometimes get scum in boilers, on heating elements and in hot water pipes. One way of keeping it at bay is to keep the temperature of the water running through these systems below 60 degrees.
You can have water filters installed on your taps or water supply pipes to trap the calcium. This can also help to avoid limescale build-up in your pipework.
If you want to get soft water in your house, you can fit a household water softener. It will need to meet the requirements of Water Supply (Water Fittings) Regulations 1999.
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.
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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