WaterHard.uk

How Hard Is Your Water?

Check water hardness for any UK postcode. See your area's PPM level, what it means for your home, and how to fix it.

Covering 2,289 postcode districts across the UK

2,289
Postcodes Covered
15
Water Companies
207 ppm
UK Average
Hard
Average Classification

How It Works

1

Enter Your Postcode

Type any UK postcode into the search box above to find your area's water hardness level.

2

See Your Results

Get your PPM reading, hardness classification, water company, and comparison to the UK average.

3

Take Action

Explore solutions, read our guides, and find the right products to manage hard water in your home.

Top 10 Hardest Water Areas in the UK

# Postcode Town Water Company Hardness Level
1 CM19 Harlow Anglian Water
394 ppm
Very Hard
2 CM18 Harlow Anglian Water
393 ppm
Very Hard
3 IP33 Bury St Edmunds Anglian Water
393 ppm
Very Hard
4 CM17 Harlow Anglian Water
392 ppm
Very Hard
5 IP32 Bury St Edmunds Anglian Water
392 ppm
Very Hard
6 NR19 Dereham Anglian Water
392 ppm
Very Hard
7 CM16 Epping Anglian Water
391 ppm
Very Hard
8 IP31 Bury St Edmunds Anglian Water
391 ppm
Very Hard
9 NR18 Wymondham Anglian Water
391 ppm
Very Hard
10 CM15 Brentwood Anglian Water
390 ppm
Very Hard

See full top 50 →

Top 10 Softest Water Areas in the UK

# Postcode Town Water Company Hardness Level
1 SY11 Oswestry Welsh Water (Dwr Cymru)
20 ppm
Soft
2 SY12 Ellesmere Welsh Water (Dwr Cymru)
21 ppm
Soft
3 SY13 Whitchurch Welsh Water (Dwr Cymru)
22 ppm
Soft
4 SY14 Malpas Welsh Water (Dwr Cymru)
23 ppm
Soft
5 SY15 Montgomery Welsh Water (Dwr Cymru)
24 ppm
Soft
6 SY16 Newtown Welsh Water (Dwr Cymru)
25 ppm
Soft
7 SY17 Caersws Welsh Water (Dwr Cymru)
26 ppm
Soft
8 TA10 Langport South West Water
27 ppm
Soft
9 SY18 Llanidloes Welsh Water (Dwr Cymru)
27 ppm
Soft
10 TQ10 South Brent South West Water
28 ppm
Soft

See full top 50 →

UK Water Companies

Anglian Water

Avg: 321 ppm Very Hard
261 postcodes

Thames Water

Avg: 302 ppm Very Hard
412 postcodes

South East Water

Avg: 297 ppm Hard
17 postcodes

Affinity Water

Avg: 268 ppm Hard
32 postcodes

Southern Water

Avg: 263 ppm Hard
131 postcodes

Portsmouth Water

Avg: 261 ppm Hard
34 postcodes

SES Water

Avg: 239 ppm Hard
7 postcodes

Wessex Water

Avg: 231 ppm Hard
123 postcodes

Severn Trent Water

Avg: 222 ppm Hard
345 postcodes

Yorkshire Water

Avg: 215 ppm Hard
217 postcodes

Northumbrian Water

Avg: 101 ppm Slightly Hard
122 postcodes

South West Water

Avg: 80 ppm Slightly Hard
129 postcodes

United Utilities

Avg: 77 ppm Slightly Hard
242 postcodes

Welsh Water (Dwr Cymru)

Avg: 68 ppm Slightly Hard
214 postcodes

Scottish Water

Avg: 54 ppm Soft
3 postcodes

Browse by Region

East Of England

326 ppm avg
Very Hard

London

286 ppm avg
Hard

South East

274 ppm avg
Hard

East Midlands

248 ppm avg
Hard

West Midlands

215 ppm avg
Hard

Yorkshire

215 ppm avg
Hard

South West

161 ppm avg
Moderately Hard

North East

101 ppm avg
Slightly Hard

North West

90 ppm avg
Slightly Hard

Wales

68 ppm avg
Slightly Hard

View all regions →

Water Hardness Guides

What Is Water Hardness?

Understanding PPM, calcium carbonate, and why it matters for your home.

Hard Water Effects

How hard water impacts your skin, hair, appliances, and energy bills.

Hard Water Solutions

Water softeners, filters, and other ways to deal with hard water.

Water Softener Guide

Types of water softeners, how they work, costs, and our top picks.

Limescale Removal

Proven methods to remove limescale from kettles, taps, showerheads, and boilers.

Water Hardness Test

Five ways to test your water hardness at home, from free tools to lab-grade accuracy.

Hard Water & Skin

How hard water causes dry skin and eczema, plus research-backed solutions.

Hard Water & Hair

Why hard water damages hair, fades colour, and how to fix it.

Hard Water & Boilers

How limescale damages boilers, increases energy costs, and how to protect yours.

Shower Filter Guide

Best shower filters for hard water compared, with installation guide.

Understanding Water Hardness in the UK

Water hardness measures the concentration of dissolved calcium and magnesium minerals in your tap water, expressed in parts per million (ppm) of calcium carbonate. In the UK, water hardness varies dramatically by region — from as low as 20 ppm in parts of Scotland and Wales to over 400 ppm in London and the South East.

The main cause is geology. Rainwater picks up minerals as it passes through chalk and limestone rock formations. Areas with granite or slate bedrock — like the Scottish Highlands, Lake District, and Cornwall — naturally have softer water. The chalk downs of southern England produce some of the hardest water in Europe.

How Water Hardness Is Classified

The UK classifies water hardness into five levels based on calcium carbonate concentration:

  • Soft: 0–60 ppm — no limescale, gentle on skin
  • Slightly Hard: 61–120 ppm — minimal limescale
  • Moderately Hard: 121–180 ppm — some limescale build-up
  • Hard: 181–300 ppm — noticeable limescale, affects appliances
  • Very Hard: 300+ ppm — heavy limescale, water softener recommended

Why It Matters for Your Home

Hard water is safe to drink, but it costs UK households an estimated £200 per year in extra energy bills, shorter appliance lifespans, and cleaning products. Limescale insulates your boiler's heat exchanger, making it work harder. A 1mm layer of limescale on a heating element reduces efficiency by up to 7%.

Check your postcode above to see your local water hardness level and what it means for your home.

Frequently Asked Questions

How do I check water hardness by postcode?
Enter your UK postcode in the search box above. WaterHard.uk covers all postcode districts and will show your area's hardness in PPM, the classification (soft to very hard), your water company, and recommended products.
What is considered hard water in the UK?
Water above 180 ppm (parts per million) calcium carbonate is classified as hard. Above 300 ppm is very hard. The UK average is around 230 ppm. London and the South East have the hardest water, while Scotland and Wales tend to be soft.
Is hard water bad for you?
Hard water is safe to drink and even provides beneficial calcium and magnesium. However, it causes limescale in kettles, boilers, and pipes, can dry out skin and hair, and reduces the effectiveness of soap and detergent.
How can I soften my water at home?
The most effective option is a whole-house ion-exchange water softener (from around £400). For smaller budgets, a shower filter (£20–30) protects skin and hair, a jug filter improves drinking water taste, and scale inhibitors protect pipes and boilers.
Which water company has the hardest water?
Thames Water, Affinity Water, and South East Water typically report the highest hardness levels, often above 300 ppm. Scottish Water and United Utilities (North West England) generally supply the softest water.

Get Water Hardness Updates

Be notified when your water company reports changes to hardness levels.