Water hardness

SO15 Southampton

Harder than the UK average. Expect visible limescale on kettles and taps.

At 187 ppm, Southampton sits among the UK's hardest water areas — compare it against the softest areas.

Hard 187 ppm South East Severn Trent Water
Your reading
187
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 187 ppm in Southampton (hard water).

  • Significant limescale buildup in kettles, pipes and boilers
  • Soap scum on shower screens and taps
  • Higher energy bills from scale in heating elements
  • Dry skin and dull hair after washing
  • White residue on dishes and glassware
Heat loss
4%
Light scaling
Softener salt
£11–18
per year
Worth it?
Yes
at 187 ppm
Suggested for hard water
Whole-house water softener
Best long-term protection for boilers and pipes.
From £600 installed
Shower head filter
A simple first step for limescale on tiles and glass.
From £25
Filter jug or under-sink
Improves taste and reduces kettle scale.
From £20
Softening

Should you soften the water in Southampton?

A verdict and running-cost estimate based on SO15's 187 ppm reading, for a typical 4-person household.

Softener recommended

Hardness is moderate to hard, so a softener cuts scale and soap use and usually pays back over its lifetime.

Recommended size
24k
grain capacity, regenerates ~every 14.3 days
Salt running cost
£11–18
per year (~38 kg salt)
Limescale
4%
est. heater efficiency loss. Light scaling
Soap saving
Low
Some saving: expect to use slightly less soap and detergent.

Appliance impact at 187 ppm: slight: minor descaling extends kettle/boiler life. Sized for a 4-person home; regenerates roughly every 14 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for SO15

Sourced from Severn Trent Water's published water-quality reports and public records.

Hardness measurements

Parts per million (ppm CaCO₃)187
Degrees Clark (°Clark)13.1
Degrees French (°fH)18.7
Degrees German (°dH)10.5
Calcium (mg/L Ca²⁺)75

Supplier and area

Water supplier Severn Trent Water
Region South East
County Hampshire
Hardness band Hard
UK average 207 ppm
Visit Severn Trent Water page
Official source
Severn Trent Water water-hardness report

Enter your postcode and pick a timeframe to see your area's measured water quality including hardness, with a downloadable PDF report.

Nearby

Other areas near Southampton

SO14
Southampton
186ppm
Hard
SO16
Southampton
188ppm
Hard
SO17
Southampton
189ppm
Hard
FAQ

Common questions about SO15

What is the water hardness in SO15 Southampton?
The water in SO15 Southampton has a hardness level of 187 ppm (parts per million) calcium carbonate, classified as hard. This is 20 ppm below the UK national average of 207 ppm.
Which water company supplies SO15?
SO15 Southampton is supplied by Severn Trent Water. Severn Trent Water serves the South East region.
Is the water in SO15 safe to drink?
Yes. Hard water at 187 ppm is safe to drink. Water hardness affects taste and can cause limescale, but it is not a health risk. In fact, hard water contains beneficial minerals like calcium and magnesium.
How can I reduce water hardness in SO15?
For hard water at 187 ppm, a whole-house water softener is the most effective solution. You can also use a jug filter for drinking water, descaling products for appliances, and a shower filter for better skin and hair.
What does 187 ppm water hardness mean?
187 ppm means there are 187 parts per million of calcium carbonate dissolved in the water. This is equivalent to 13.1 Clark degrees, 10.5 German degrees, or 18.7 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in SO15?
For a typical 4-person home at 187 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 14.3 days. Larger households or higher daily use need a bigger unit. These figures are conservative estimates.
How much does it cost to run a water softener in SO15?
At 187 ppm, expect to use about 38 kg of salt a year, costing roughly £11–£18/year. Hardness is moderate to hard, so a softener cuts scale and soap use and usually pays back over its lifetime.

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