Water hardness

TN15 Sevenoaks

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

At 204 ppm, Sevenoaks sits among the UK's hardest water areas — compare it against the softest areas.

Hard 204 ppm South East Southern Water
Your reading
204
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 204 ppm in Sevenoaks (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
£12–20
per year
Worth it?
Yes
at 204 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 Sevenoaks?

A verdict and running-cost estimate based on TN15's 204 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 13.1 days
Salt running cost
£12–20
per year (~42 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 204 ppm: noticeable: boiler/dishwasher life cut without descaling. Sized for a 4-person home; regenerates roughly every 13 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for TN15

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

Hardness measurements

Parts per million (ppm CaCO₃)204
Degrees Clark (°Clark)14.3
Degrees French (°fH)20.4
Degrees German (°dH)11.4
Calcium (mg/L Ca²⁺)82

Supplier and area

Water supplier Southern Water
Region South East
County Kent
Hardness band 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 Sevenoaks

TN14
Sevenoaks
203ppm
Hard
TN16
Westerham
205ppm
Hard
TN17
Cranbrook
206ppm
Hard
FAQ

Common questions about TN15

What is the water hardness in TN15 Sevenoaks?
The water in TN15 Sevenoaks has a hardness level of 204 ppm (parts per million) calcium carbonate, classified as hard. This is 3 ppm below the UK national average of 207 ppm.
Which water company supplies TN15?
TN15 Sevenoaks is supplied by Southern Water. Southern Water serves the South East region.
Is the water in TN15 safe to drink?
Yes. Hard water at 204 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 TN15?
For hard water at 204 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 204 ppm water hardness mean?
204 ppm means there are 204 parts per million of calcium carbonate dissolved in the water. This is equivalent to 14.3 Clark degrees, 11.4 German degrees, or 20.4 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in TN15?
For a typical 4-person home at 204 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 13.1 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 TN15?
At 204 ppm, expect to use about 42 kg of salt a year, costing roughly £12–£20/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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