How to measure water hardness at home

You do not have to guess. You can know your water hardness in a few minutes, from a free postcode check to a cheap drop test.

Way 1: ask your water company

Every water company in England publishes water quality by area, and most have a postcode checker on their website that gives hardness in mg/L or Clark degrees. It is free and it is the most reliable figure for the water reaching your street. Your annual water quality report shows it too.

Way 2: test strips

Total hardness test strips are sold in chemists, DIY shops and aquarium shops. Dip a strip, wait a few seconds and match the colour to the chart. It tells you the band rather than an exact number, which is usually enough to set a dishwasher or decide on a softener.

Way 3: a drop test

A drop test counts how many drops of reagent turn the sample a new colour. Each drop equals a fixed amount of hardness. It is more precise than a strip and costs a few pounds.

Why readings differ

Many towns get water from more than one source, so hardness can change from one district to the next and through the year. If you already have a softener, you will measure soft water after it, so test at an unsoftened tap, usually the kitchen cold tap.

Using your result

Set the dishwasher's water-hardness setting and salt use from your result, dose laundry detergent as the pack says for your band, and plan how often to descale. If your water is soft, you do not need a softener.