Water hardness

SM5 Carshalton

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

At 240 ppm, Carshalton sits among the UK's hardest water areas — compare it against the softest areas.

Hard 240 ppm London SES Water
Your reading
240
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 240 ppm in Carshalton (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
8%
Moderate scaling
Softener salt
£14–23
per year
Worth it?
Yes
at 240 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 Carshalton?

A verdict and running-cost estimate based on SM5's 240 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 11.2 days
Salt running cost
£14–23
per year (~49 kg salt)
Limescale
8%
est. heater efficiency loss. Moderate scaling
Soap saving
Moderate
Noticeable saving: soaps lather more easily, cutting detergent use.

Appliance impact at 240 ppm: noticeable: boiler/dishwasher life cut without descaling. Sized for a 4-person home; regenerates roughly every 11 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for SM5

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

Hardness measurements

Parts per million (ppm CaCO₃)240
Degrees Clark (°Clark)16.8
Degrees French (°fH)24
Degrees German (°dH)13.4
Calcium (mg/L Ca²⁺)96

Supplier and area

Water supplier SES Water
Region London
County Greater London
Hardness band Hard
UK average 207 ppm
Visit SES Water page
Official source
SES Water water-hardness report

Enter your full postcode to pull your supply zone report showing average hardness plus other drinking water test results.

Nearby

Other areas near Carshalton

SM4
Morden
239ppm
Hard
SM6
Wallington
241ppm
Hard
SM7
Banstead
242ppm
Hard
FAQ

Common questions about SM5

What is the water hardness in SM5 Carshalton?
The water in SM5 Carshalton has a hardness level of 240 ppm (parts per million) calcium carbonate, classified as hard. This is 33 ppm above the UK national average of 207 ppm.
Which water company supplies SM5?
SM5 Carshalton is supplied by SES Water. SES Water serves the London region.
Is the water in SM5 safe to drink?
Yes. Hard water at 240 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 SM5?
For hard water at 240 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 240 ppm water hardness mean?
240 ppm means there are 240 parts per million of calcium carbonate dissolved in the water. This is equivalent to 16.8 Clark degrees, 13.4 German degrees, or 24 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in SM5?
For a typical 4-person home at 240 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 11.2 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 SM5?
At 240 ppm, expect to use about 49 kg of salt a year, costing roughly £14–£23/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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