UK region

Water hardness in South East

Average 274 ppm across 352 postcode districts, classified as hard.

  • Range 163 to 350 ppm
  • Counties 8
  • Suppliers Affinity Water, Anglian Water, Portsmouth Water, Severn Trent Water, Southern Water, Thames Water
Regional average
274
ppm CaCO₃
Hard
Soft
Moderate
Hard
Very hard
0100200300400+
274
Avg ppm
163
Min ppm
350
Max ppm
352
Postcodes

South East water hardness at a glance

  1. South East water is hard, averaging 274 ppm across 352 postcode districts.
  2. That is 67 ppm above the UK average of 207 ppm.
  3. Districts range from 163 ppm to 350 ppm; the hardest county is Surrey (305 ppm) and the softest is Hampshire (244 ppm).
  4. Suppliers: Affinity Water, Anglian Water, Portsmouth Water, Severn Trent Water, Southern Water, Thames Water.
  5. Expect limescale on kettles, taps and showerheads; see the water softener guide.

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Water Hardness Across South East

The average water hardness in the South East region is 274 ppm, classified as hard. Across 352 postcode districts, hardness ranges from 163 ppm to 350 ppm.

Is the water in South East hard or soft? It is hard, with readings from 163 to 350 ppm. Most postcodes here are supplied by Southern Water or Thames Water; cross-check against Southern Water's own water hardness data or Thames Water's.

The region is served by Affinity Water, Anglian Water, Portsmouth Water, Severn Trent Water, Southern Water, Thames Water. Water hardness varies by county; see the breakdown below or check your specific postcode.

Hardness varies notably within South East: Surrey has the hardest water in the region at 305 ppm, while Hampshire is the softest at 244 ppm. The region spans 14 towns and 352 postcode districts in total.

At 274 ppm, South East ranks as hard water nationally. Compare it against the 50 hardest water areas in the UK.

Worth reading: our water softener guide covers the best options for South East residents, and our limescale removal guide has quick fixes for kettles and taps.

By county

Counties in South East

Sorted by hardness: see how your county compares.

County Hardness PPM Level Postcodes
Surrey
305
305 ppm Very Hard 58
Oxfordshire
304
304 ppm Very Hard 26
Hertfordshire
303
303 ppm Very Hard 53
Buckinghamshire
301
301 ppm Very Hard 26
Berkshire
291
291 ppm Hard 40
East Sussex
271
271 ppm Hard 30
Kent
246
246 ppm Hard 81
Hampshire
244
244 ppm Hard 57
Suppliers

Water Companies in South East

Tap on a company for full coverage area and hardness data.

Affinity Water

268 ppm Hard

Anglian Water

321 ppm Very Hard

Portsmouth Water

261 ppm Hard

Severn Trent Water

222 ppm Hard

Southern Water

263 ppm Hard

Thames Water

302 ppm Very Hard

Hard Water Guides

Learn more about water hardness and how to manage it.

What Is Water Hardness? Hard Water Effects Solutions
Recommended

Products for South East

Top picks for households in hard water areas.

Splendid Twin Tank Water Softener

Twin-tank electric softener sized for 1 to 7 bedroom homes. Removes limescale from pipes, boilers, and appliances and delivers continuous soft water, with metered regeneration to keep salt use low.

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Philips Shower Filter

Instant improvement for skin and hair. Reduces chlorine and limescale at the showerhead, no plumbing needed. A good first step before committing to a full softener.

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FAQ

Common questions about South East water

Is South East's water hard or soft?
South East is classified as hard water, averaging 274 ppm across 352 postcode districts. Expect visible limescale on kettles and taps within weeks at this level.
Is tap water in South East safe to drink?
Hardness is not a safety issue: the World Health Organization sets no health-based limit for water hardness, so hard and soft water are both fine to drink. Drinking water quality is regulated by the Drinking Water Inspectorate in England and Wales and the Drinking Water Quality Regulator in Scotland, and your water company publishes test results for your area.
Why is water in South East hard?
Water hardness in South East depends on the geology: chalk and limestone aquifers dissolve calcium and magnesium into the supply, making it harder. Areas with sandstone or granite tend to be softer.
Does hard water affect boilers in South East?
Over time, limescale acts as an insulator in heat exchangers, reducing efficiency by a few percentage points each year if untreated. A water softener can help protect your boiler.
What's the average water hardness in South East?
The average water hardness across South East is 274 ppm (parts per million), classified as hard. It ranges from 163 ppm to 350 ppm across 352 postcode districts.
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