Water hardness in Preston

Preston has moderately soft water: about 83 mg/l of calcium carbonate (5.81 degrees Clark) in the Preston Central (Z077) supply zone. Source: the United Utilities water quality lookup for a PR1 city-centre postcode, register updated 16 October 2026. Last checked 18 October 2026.

Preston's water is moderately soft. United Utilities' register gives the Preston Central zone a typical hardness of about 83 mg/l of calcium carbonate, with a note that the supply can vary from soft to slightly hard depending on which source is feeding the zone on the day.

What Preston water means at home

Kettles and appliances

A thin film of scale over a few months rather than thick deposits. Descale a kettle two or three times a year and keep the dishwasher on a low hardness setting.

Skin and hair

Lathering is easy and most people notice no effect on skin or hair at this level.

Pipes and metals

Water in this band still dissolves a little metal from old pipework, so a first-draw sample from a pre-1970 home is worth checking for lead and copper before you worry about scale.

Where Preston's water comes from

This is one of the more mixed supplies in Lancashire: United Utilities lists upland sources, groundwater sources and river sources for the zone. Groundwater from the Fylde sandstone is harder than the reservoir water from the moors, so the blend shifts and so does the hardness. That is the reason the register gives a range rather than a single figure.

United Utilities says: "The water supply to this area comes from upland sources, groundwater sources and river sources." "The water supply to this area can vary in hardness from soft to slightly hard."

If your kettle furs up faster than a neighbour's across town, the two of you may simply be on different parts of the blend. Test on different days and you will often see the hardness pad move by one colour step. The results portal keeps each reading, so the pattern shows up over a few weeks.

The hardness scale, and where Preston sits

Band Calcium carbonate
Soft 0 to 50 mg/l
Moderately soft (Preston) 51 to 100 mg/l
Slightly hard 101 to 150 mg/l
Moderately hard 151 to 200 mg/l
Hard 201 to 300 mg/l
Very hard over 300 mg/l

Bands follow the six-band scale used by United Utilities and most water companies and shown on the Drinking Water Inspectorate's hardness map. The DWI's own web page groups the first two bands together as soft (up to 100 mg/l). One degree Clark is about 14.3 mg/l of calcium carbonate. The Water Supply (Water Quality) Regulations 2016 set no limit for hardness.

Check your own tap in 60 seconds

The figure above is a zone average, and in a blended supply your tap can sit anywhere in the range the water company quotes. The WaterKit Drinking Water Test Kit reads hardness, alkalinity, pH, copper, lead and 15 other checks from one strip dipped in the sample tube, and the results portal explains each reading against the UK limit where one exists. From £12.99 with a 30-day money-back guarantee. If you are new to strip testing, how to test your water at home walks through it.

Softener or scale filter?

At this level a softener is rarely worth the outlay: scale builds slowly and a kettle descale two or three times a year deals with it. If you are offered one for a Preston address, ask for the hardness figure the quote is based on and compare it with a strip reading from your own tap.

Questions people in Preston ask

Why might my tap read differently from the figure on this page?

The figure is the typical value for one supply zone, and United Utilities quotes a range for the zone because the blend of sources changes. Your house may be on a neighbouring zone, and water that has stood in your own pipes can read differently from flushed water. A strip test on your own tap gives you your number.

What is the quickest way to check my water hardness at home?

A test strip. Dip one in a sample tube of tap water for two seconds, wait a minute and compare the hardness pad with the colour chart; the WaterKit strip reads 19 other things at the same time, including pH, copper and lead. Water companies also publish the zone figure, which is where the number on this page comes from.

Why does Preston's hardness change from week to week?

Because the zone is fed by a blend of upland reservoir water, groundwater and river water, and the proportions change from week to week. Groundwater is the hardest of the three, so weeks with more of it in the mix read higher. United Utilities quotes soft to slightly hard for the zone for that reason.

Where does the figure on this page come from?

From the United Utilities water quality lookup for Preston, checked on 18 October 2026. You can run the same lookup for your postcode on their website and compare.

Is Preston a hard water area?

No. Preston is a moderately soft water area, with a typical reading of about 83 mg/l of calcium carbonate for the city-centre zone. That is the second of six bands and well under the hard band, which starts at 201 mg/l. Streets on a different supply zone can read higher or lower.

Is hard or soft water a health issue?

Neither is. There is no UK legal limit for hardness because it does not affect health; the Regulations 2016 list limits for things like lead, copper and nitrate but not for calcium and magnesium. Hardness matters for kettles, washing and pipework, not for drinking.

For the general picture, see hard water, explained.

Sources

Contains public sector information licensed under the Open Government Licence v3.0. Hardness figures are typical values for one supply zone and change as the blend of sources changes; they are quoted for information and are not a substitute for a reading on your own tap.