Water hardness

DA14 Sidcup

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

At 258 ppm, Sidcup sits among the UK's hardest water areas — compare it against the softest areas.

Hard 258 ppm London Thames Water
Your reading
258
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 258 ppm in Sidcup (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
£15–25
per year
Worth it?
Yes
at 258 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 Sidcup?

A verdict and running-cost estimate based on DA14's 258 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 10.4 days
Salt running cost
£15–25
per year (~53 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 258 ppm: noticeable: boiler/dishwasher life cut without descaling. Sized for a 4-person home; regenerates roughly every 10 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for DA14

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

Hardness measurements

Parts per million (ppm CaCO₃)258
Degrees Clark (°Clark)18.1
Degrees French (°fH)25.8
Degrees German (°dH)14.5
Calcium (mg/L Ca²⁺)103

Supplier and area

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

Read the hardness categories table to see where your supply falls; most of the region is hard to very hard at over 200 mg/l CaCO3.

Nearby

Other areas near Sidcup

DA13
Gravesend
257ppm
Hard
DA15
Sidcup
259ppm
Hard
DA16
Welling
260ppm
Hard
FAQ

Common questions about DA14

What is the water hardness in DA14 Sidcup?
The water in DA14 Sidcup has a hardness level of 258 ppm (parts per million) calcium carbonate, classified as hard. This is 51 ppm above the UK national average of 207 ppm.
Which water company supplies DA14?
DA14 Sidcup is supplied by Thames Water. Thames Water serves the London region.
Is the water in DA14 safe to drink?
Yes. Hard water at 258 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 DA14?
For hard water at 258 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 258 ppm water hardness mean?
258 ppm means there are 258 parts per million of calcium carbonate dissolved in the water. This is equivalent to 18.1 Clark degrees, 14.5 German degrees, or 25.8 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in DA14?
For a typical 4-person home at 258 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 10.4 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 DA14?
At 258 ppm, expect to use about 53 kg of salt a year, costing roughly £15–£25/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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