My water supply

Water hardness

When water falls as rain, it's "soft" and free of minerals.

It picks up naturally occurring minerals, such as calcium and magnesium, as it passes through rock, sand and soil. This causes the water to become ‘hard.’

All the water we supply is ‘hard’ together with more than 60% of homes in the UK.

The picture shows a comparison with other areas in the UK. 


Water Hardness in the UK

Hard water in your home

Find out more about hard water in your home

Find out how hard the water is in your home

1. Find the water quality zone for your area

2. Use the water quality zone to read the table below:

Zone Zone Name Hardness
Z1 Cambridge North Hard to very hard
Z2 Cambridge South Hard to very hard
Z3 Cambridge Rural Hard to very hard
Z4 Linton Hard to very hard
Z5 Heydon Hard to very hard
Z6 Coton Hard to very hard
Z8 Odsey Hard to very hard
Z9 Bluntisham Hard to very hard
Z10 Earith Bridge Hard to very hard

Download the full water hardness data report.