Water hardness

TR21 Isles Of Scilly

Near or below the UK average. Limescale builds slowly.

At 103 ppm, Isles Of Scilly ranks near the UK's softest water areas — compare it against the hardest areas.

Slightly Hard 103 ppm South West South West Water
Your reading
103
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 103 ppm in Isles Of Scilly (slightly hard water).

  • Minor limescale may appear in kettles over time
  • Soap lathers reasonably well
  • Appliances generally unaffected
  • Good balance of mineral taste
Heat loss
4%
Light scaling
Softener salt
£6–10
per year
Worth it?
No
at 103 ppm
Suggested for slightly hard water
Filter jug (optional)
Mainly a taste preference, limescale won't be a real issue here.
From £20
Maintenance habits
Routine descaling once or twice a year is plenty.
Free
Softening

Should you soften the water in Isles Of Scilly?

A verdict and running-cost estimate based on TR21's 103 ppm reading, for a typical 4-person household.

Softener optional

Water is soft to moderate, so limescale and soap costs are low and a softener rarely pays back.

Recommended size
24k
grain capacity, regenerates ~every 26 days
Salt running cost
£6–10
per year (~21 kg salt)
Limescale
4%
est. heater efficiency loss. Light scaling
Soap saving
Low
Some saving: expect to use slightly less soap and detergent.

Appliance impact at 103 ppm: slight: minor descaling extends kettle/boiler life. Sized for a 4-person home; regenerates roughly every 26 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for TR21

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

Hardness measurements

Parts per million (ppm CaCO₃)103
Degrees Clark (°Clark)7.2
Degrees French (°fH)10.3
Degrees German (°dH)5.8
Calcium (mg/L Ca²⁺)41

Supplier and area

Water supplier South West Water
Region South West
County Cornwall
Hardness band Slightly Hard
UK average 207 ppm
Visit South West Water page
Official source
South West Water water-hardness report

Most of the region is soft water, except East Devon; use the postcode lookup on this page to find your address's specific water quality.

Nearby

Other areas near Isles Of Scilly

TR20
Penzance
102ppm
Slightly Hard
FAQ

Common questions about TR21

What is the water hardness in TR21 Isles Of Scilly?
The water in TR21 Isles Of Scilly has a hardness level of 103 ppm (parts per million) calcium carbonate, classified as slightly hard. This is 104 ppm below the UK national average of 207 ppm.
Which water company supplies TR21?
TR21 Isles Of Scilly is supplied by South West Water. South West Water serves the South West region.
Is the water in TR21 safe to drink?
Yes. Slightly Hard water at 103 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 TR21?
At 103 ppm, the water in TR21 is slightly hard and unlikely to cause significant issues. A jug filter can improve taste, but a water softener is generally not necessary.
What does 103 ppm water hardness mean?
103 ppm means there are 103 parts per million of calcium carbonate dissolved in the water. This is equivalent to 7.2 Clark degrees, 5.8 German degrees, or 10.3 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in TR21?
For a typical 4-person home at 103 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 26 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 TR21?
At 103 ppm, expect to use about 21 kg of salt a year, costing roughly £6–£10/year. Water is soft to moderate, so limescale and soap costs are low and a softener rarely pays back.

Your Isles Of Scilly water action plan

Enter your email for the short list of things worth doing at 103 ppm, and the upgrades you can safely ignore.

Check another postcode

Compare hardness across areas before moving or buying a softener.