Is Preston Water Hard or Soft? What It Means for Your Boiler and Bathroom
Short answer: most of Preston has soft water. But not everywhere — and it makes a difference to limescale, how long your shower head stays clear, and whether a scale reducer is worth fitting with a new boiler.
The figures
Preston's water is supplied by United Utilities. These are the 12-month average hardness figures for the main local supply zones (as published in September 2026):
| Supply zone | Hardness | Classed as |
|---|---|---|
| Preston Central | 85 mg/l | Soft |
| Preston South | 93 mg/l | Soft |
| Preston West | 84 mg/l | Soft |
| Preston Cow Hill | 82 mg/l | Soft |
| Preston/Fulwood | 136 mg/l | Slightly hard |
| Dilworth (Longridge) | 57 mg/l | Soft |
| Barnacre (parts of PR3) | 144 mg/l | Slightly hard |
Which zone you're in depends on your street, not just your postcode. For your exact address, United Utilities can send you a water quality report.
What soft water means for you
- Less limescale on taps, glass shower screens and kettles.
- Shower heads and aerators stay clear for longer.
- Less scale inside combi boilers, whose hot water heat exchangers are the part most affected by hard water.
- A water softener usually isn't needed. In most of Preston, it's money you don't need to spend.
If you're in a slightly hard area
Parts of Fulwood and some of PR3 sit on slightly harder supplies. It's nowhere near the hard water you get in the South East, but you'll see a bit more scale. Descale shower heads now and then, and when we fit a new combi there, we'll talk through whether an inline scale reducer is worth adding. Some boiler manufacturers make scale protection part of their installation requirements above certain hardness levels, so it's worth getting right.
Soft water and your heating
Soft water doesn't cause sludge. Sludge in radiators comes from corrosion inside the heating system, which is a closed loop that has nothing to do with your tap water. If your radiators are cold at the bottom, that's a different problem — see radiator cold at the bottom? and power flushing explained.
Low pressure or scaled-up shower?
Our guide to low water pressure covers descaling and the other usual causes.
Thinking about a new boiler? See our boiler cost guide, or call 07949 075721 for a free quote.