Water hardness

RH4 Dorking

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

At 324 ppm, Dorking sits among the UK's hardest water areas — compare it against the softest areas.

Very Hard 324 ppm South East Southern Water
Your reading
324
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 324 ppm in Dorking (very hard water).

  • Heavy limescale requiring frequent descaling
  • Blocked showerheads and reduced water flow
  • Substantially higher energy bills from boiler scale
  • Dry, itchy skin and lifeless hair
  • White crusty deposits on taps and surfaces
  • Reduced lifespan of washing machines and dishwashers
Heat loss
12%
Heavy scaling
Softener salt
£18–32
per year
Worth it?
Yes
at 324 ppm
Suggested for very 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 Dorking?

A verdict and running-cost estimate based on RH4's 324 ppm reading, for a typical 4-person household.

Softener recommended

Water is hard to very hard, so appliance, scale and soap savings typically pay back a softener within a few years.

Recommended size
24k
grain capacity, regenerates ~every 8.3 days
Salt running cost
£18–32
per year (~66 kg salt)
Limescale
12%
est. heater efficiency loss. Heavy scaling
Soap saving
High
Large saving: many homes cut soap, shampoo and detergent use by up to half.

Appliance impact at 324 ppm: significant: elements fur up, expect earlier failures. Sized for a 4-person home; regenerates roughly every 8 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for RH4

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

Hardness measurements

Parts per million (ppm CaCO₃)324
Degrees Clark (°Clark)22.7
Degrees French (°fH)32.4
Degrees German (°dH)18.2
Calcium (mg/L Ca²⁺)130

Supplier and area

Water supplier Southern Water
Region South East
County Surrey
Hardness band Very Hard
UK average 207 ppm
Visit Southern Water page
Official source
Southern Water water-hardness report

Enter your postcode in the hard water checker to get your hardness band and a full water quality report in mg/l, Clarke, French or German degrees.

Nearby

Other areas near Dorking

RH3
Betchworth
323ppm
Very Hard
RH5
Dorking
325ppm
Very Hard
RH6
Horley
326ppm
Very Hard
FAQ

Common questions about RH4

What is the water hardness in RH4 Dorking?
The water in RH4 Dorking has a hardness level of 324 ppm (parts per million) calcium carbonate, classified as very hard. This is 117 ppm above the UK national average of 207 ppm.
Which water company supplies RH4?
RH4 Dorking is supplied by Southern Water. Southern Water serves the South East region.
Is the water in RH4 safe to drink?
Yes. Very Hard water at 324 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 RH4?
For very hard water at 324 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 324 ppm water hardness mean?
324 ppm means there are 324 parts per million of calcium carbonate dissolved in the water. This is equivalent to 22.7 Clark degrees, 18.2 German degrees, or 32.4 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in RH4?
For a typical 4-person home at 324 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 8.3 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 RH4?
At 324 ppm, expect to use about 66 kg of salt a year, costing roughly £18–£32/year. Water is hard to very hard, so appliance, scale and soap savings typically pay back a softener within a few years.

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