Southampton water is extremely hard and I have had a water softener for a number of years. Very well worth while! When we last replaced the boiler I kept the loft cold water tank (supplying the HW cylinder) fed from the softener as it made it easy to arrange a softened cold feed to the upstairs bath and shower pump. Unfortunately the geometry made it impractical to run the downstairs electric shower from the softened supply, but it doesn’t get used as often anyway.
Niall