How much sodium will be in my water when softened?

What is hard water?

Rainwater that is naturally soft tends to pick up minerals, such as calcium and magnesium, as it flows through the ground. When it encounters rocks, like chalk and limestone, it can absorb up high levels of these minerals and result in hard water.

Is my water hard or soft?

If you live in certain parts of UK you may have hard or very hard water (see map below from waterwise for a rugh idea).


Hardness may vary from postcode to postcode, so please contact your water supply company for information on the specific level of hardness in your water.

Should I soften my water?

Please follow the links below for detailed information about hard and soft water and its potential impact on your house and health.

Water softeners work by an ion exchange process that to removes the hardness minerals and replaces them with sodium which does not cause scaling.

The calculator below helps you estimating the final amount of sodium in your softened water using the formula from Harvey Water Stones (page 8).

The user must provide the pre-softening amount of Calcium Carbonate (CaCO3) and the amount of Sodium (as Na). These values can be found by asking your water supplier (such as Thames Water).

To have an idea of acceptable levels of sodium in water, checkout this document from Anglian Water.

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