UK region

Water hardness in South East

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

Range 163–350 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

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.

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.

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

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.

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

From ~£400

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.

View on Amazon

Philips Shower Filter

From ~£30

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.

View on Amazon

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?

Yes. All tap water in South East meets UK drinking water standards. Hardness affects taste and limescale buildup but not safety.

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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