Average 91 ppm across 23 postcodes and 1 towns.
The average water hardness in Cornwall is 91 ppm, classified as slightly hard. Across 23 postcode districts in the South West region, hardness ranges from 69 ppm to 109 ppm.
Cornwall is served by South West Water. With slightly hard water, limescale is unlikely to be a major concern in most homes.
Sorted by hardness — tap a town for full details.
Companies supplying water to this county.
Every postcode district in the county, sorted by hardness.
Learn more about water hardness and how to manage it.
Be notified when water companies in Cornwall report changes to hardness levels.