Water hardness

CB21 Cambridge

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

At 369 ppm, Cambridge sits among the UK's hardest water areas — compare it against the softest areas.

Very Hard 369 ppm East Of England Anglian Water
Your reading
369
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 369 ppm in Cambridge (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
£21–36
per year
Worth it?
Yes
at 369 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 Cambridge?

A verdict and running-cost estimate based on CB21's 369 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 7.3 days
Salt running cost
£21–36
per year (~75 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 369 ppm: significant: elements fur up, expect earlier failures. Sized for a 4-person home; regenerates roughly every 7 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for CB21

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

Hardness measurements

Parts per million (ppm CaCO₃)369
Degrees Clark (°Clark)25.8
Degrees French (°fH)36.9
Degrees German (°dH)20.7
Calcium (mg/L Ca²⁺)148

Supplier and area

Water supplier Anglian Water
Region East Of England
County Cambridgeshire
Hardness band Very Hard
UK average 207 ppm
Visit Anglian Water page
Official source
Anglian Water Services Ltd water-hardness report

Read the hard water explainer then use the linked postcode checker to confirm if you are in a hard water area; the region averages very hard.

Nearby

Other areas near Cambridge

CB22
Cambridge
370ppm
Very Hard
CB23
Cambridge
371ppm
Very Hard
FAQ

Common questions about CB21

What is the water hardness in CB21 Cambridge?
The water in CB21 Cambridge has a hardness level of 369 ppm (parts per million) calcium carbonate, classified as very hard. This is 162 ppm above the UK national average of 207 ppm.
Which water company supplies CB21?
CB21 Cambridge is supplied by Anglian Water. Anglian Water serves the East Of England region.
Is the water in CB21 safe to drink?
Yes. Very Hard water at 369 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 CB21?
For very hard water at 369 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 369 ppm water hardness mean?
369 ppm means there are 369 parts per million of calcium carbonate dissolved in the water. This is equivalent to 25.8 Clark degrees, 20.7 German degrees, or 36.9 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in CB21?
For a typical 4-person home at 369 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 7.3 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 CB21?
At 369 ppm, expect to use about 75 kg of salt a year, costing roughly £21–£36/year. Water is hard to very hard, so appliance, scale and soap savings typically pay back a softener within a few years.

Check another postcode

Compare hardness across areas before moving or buying a softener.