What is water hardness?

Water hardness is determined by the amount of calcium and magnesium carbonate present in the water. These minerals dissolve into the rainwater (which is naturally soft) as it flows through limestone or sandstone, the water passes through it makes it hard.

As the water passes through limestone and sandstone rocks, minerals (calcium or magnesium carbonate) in the rocks are dissolved in the water, making it hard.

Do you have hard water?

Rainwater is naturally soft as it contains only small amounts of minerals.

Most of our water supply can be classified as ‘moderately hard’ (on a scale of one to ten this would be seven).

Search the quality of your drinking water

Enter your full postcode to learn more about the quality of the drinking water in your home.
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How to look after my appliances

Depending on how hard your water is, the way you use your appliances, and use water in general, may need to change.

You might also experience some staining issues - our handy guide on staining will help you work out why.

Appliance Soft water - what to do Hard water - what to do
Kettle No special requirements, although you might notice discolouration over time. Avoid boiling the same water more than once to reduce limescale build-up. 
Boiler and central heating No special requirements. Setting the boiler to 60-63 degrees can help avoid limescale.
Iron No special requirements. Use the lowest appropriate temperature to reduce limescale build-up.
Washing machine Use the lower amounts of washing powders and fabric conditioners recommended by manufacturers

You may find you need to use more powder and conditioners to get soapy water, and limescale may build up in the machine over time.

Dishwashers Use the lower settings recommended by manufacturers. Use the higher settings for softening as recommended by the manufacturer. You might also consider using salt tablets, as these help reduce the risk of scale build up.
Baths and fittings No special requirements. Unfortunately, one of the bugbears of having hard water is the limescale build up on things like taps, tiles, and showerheads. However, you can keep on top of it by regularly using anti-limescale cleaners.
Using soap and washing up liquid Only use small amounts – it’s all you’ll need to get a good lather. You might find you have to use more soap to build up a good lather, and it might take a while because hard water is not bubble-friendly. But the effectiveness of the soap remains the same, regardless of the number of bubbles.

Water softeners

If your water is classed as hard, you may choose to install water softeners in your home. 

However, the Drinking Water Inspectorate recommends you don’t soften drinking water because it can increase the levels of sodium which is harmful if you have high blood pressure. It can also be more corrosive to metal pipework which leads to higher concentrations of metal in the water.