Water hardness

AL5 Harpenden

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

At 243 ppm, Harpenden sits among the UK's hardest water areas — compare it against the softest areas.

Hard 243 ppm South East Affinity Water
Your reading
243
parts per million
Soft
Moderate
Hard
Very hard
0100200300400+

What this means for your home

Based on 243 ppm in Harpenden (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
£14–24
per year
Worth it?
Yes
at 243 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 Harpenden?

A verdict and running-cost estimate based on AL5's 243 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 11 days
Salt running cost
£14–24
per year (~50 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 243 ppm: noticeable: boiler/dishwasher life cut without descaling. Sized for a 4-person home; regenerates roughly every 11 days (estimate). Figures are conservative estimates and vary with household size and usage.

Water quality details

Hardness data for AL5

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

Hardness measurements

Parts per million (ppm CaCO₃)243
Degrees Clark (°Clark)17
Degrees French (°fH)24.3
Degrees German (°dH)13.6
Calcium (mg/L Ca²⁺)97

Supplier and area

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

Enter your postcode to see your water hardness level, useful for setting your dishwasher, washing machine, or water softener.

Nearby

Other areas near Harpenden

AL4
St Albans
242ppm
Hard
AL6
Welwyn
244ppm
Hard
AL7
Welwyn Garden City
245ppm
Hard
FAQ

Common questions about AL5

What is the water hardness in AL5 Harpenden?
The water in AL5 Harpenden has a hardness level of 243 ppm (parts per million) calcium carbonate, classified as hard. This is 36 ppm above the UK national average of 207 ppm.
Which water company supplies AL5?
AL5 Harpenden is supplied by Affinity Water. Affinity Water serves the South East region.
Is the water in AL5 safe to drink?
Yes. Hard water at 243 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 AL5?
For hard water at 243 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 243 ppm water hardness mean?
243 ppm means there are 243 parts per million of calcium carbonate dissolved in the water. This is equivalent to 17 Clark degrees, 13.6 German degrees, or 24.3 French degrees. Water above 180 ppm is generally considered hard.
What size water softener do I need in AL5?
For a typical 4-person home at 243 ppm, a 24,000 grain softener is a sensible size. It would regenerate roughly every 11 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 AL5?
At 243 ppm, expect to use about 50 kg of salt a year, costing roughly £14–£24/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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