Hard water in
Herts & Essex.
If you live around Bishop's Stortford, Harlow, Saffron Walden or Great Dunmow, you've seen it: white crust on taps, cloudy shower screens and kettles that fur up. Here's why, and what you can do about it.
Why the water here is hard
Much of the area's water comes from underground chalk. As rainwater soaks through the chalk it picks up calcium and magnesium — and that's what makes water hard.
Most of the towns we cover are supplied by Affinity Water. Its own 2025 reports put every supply zone around us in the Drinking Water Inspectorate's “very hard” band.
How hard is the water in our towns?
| Area (Affinity supply zone) | Average, mg/l | °Clark | Described as |
|---|---|---|---|
| Saffron Walden (AF006) | 360 | 25 | Very hard |
| Great Dunmow (AF019) | 350 | 25 | Very hard |
| Bishop's Stortford (AF018) | 345 | 24 | Very hard |
| Stansted (AF011) | 345 | 24 | Very hard |
| Sawbridgeworth (AF022) | 340 | 24 | Very hard |
| Harlow (north) (AF024) | 330 | 23 | Very hard |
| Hertford (AF021) | 318 | 22 | Very hard |
| Harlow (south) (AF094) | 310 | 22 | Very hard |
Average total hardness as calcium carbonate, 1 January – 31 December 2025, from Affinity Water's published water-quality report for each zone: AF006, AF019, AF018, AF011, AF022, AF024, AF021, AF094.
The villages in between — Elsenham, Takeley, Hatfield Heath, Hatfield Broad Oak, Sheering and Roydon — are fed from neighbouring zones, all of which averaged over 300 mg/l in 2025. Use the postcode checker below for your exact figure.
How hardness is measured
| mg/l CaCO₃ | °Clark | Described as |
|---|---|---|
| Up to 100 | Up to 7 | Soft |
| 100–150 | 7–10.5 | Slightly hard |
| 150–200 | 10.5–14 | Moderately hard |
| 200–300 | 14–21 | Hard |
| Over 300 | Over 21 | Very hard |
Bands as published by the Drinking Water Inspectorate.
Saffron Walden's water softening has stopped
For decades, water supplied to Saffron Walden was partly softened before it reached homes. That equipment reached the end of its life in 2021, and Affinity Water later decided not to reinstate it. Homes in the town now receive naturally hard water, which is why so many Saffron Walden households are looking at softeners.
What hard water does in your home
Limescale forms wherever hard water is heated or left to dry: on taps, shower heads, glass and tiles, and inside kettles, immersion heaters, hot water cylinders and appliances.
Scale on heating surfaces acts as insulation, so heat passes into the water less efficiently. You'll see a lot of percentage figures quoted online — most come from the water-treatment industry rather than independent studies, so we don't quote them. The principle is simple: less scale, cleaner heating surfaces.
Many people also find softened water kinder to skin and hair, and need far less soap and cleaning product.
Check your postcode
Your water company publishes the hardness for your postcode. Most of our area is supplied by Affinity Water — search “water hardness” on affinitywater.co.uk and enter your postcode. If your bill comes from a different company, use their website instead.
What a water softener does
A softener fitted on your incoming cold main swaps the calcium and magnesium for sodium using resin, which it regularly cleans with salt. Softened water then reaches every tap, shower and appliance in the house.
It's usual to keep one unsoftened tap at the kitchen sink for drinking and cooking — the Drinking Water Inspectorate advises this, and softened water shouldn't be used to make up baby feeds.
Read our guide to the types of water softener, or see how we fit them.
Hard water across Herts and Essex scales up taps, showers and heating. A softener fitted on the incoming main stops it at the source.
Keep reading.
Types of water softener, explained
Harvey's, Kinetico, Monarch and Tapworks compared — power, salt and regeneration.
Read the guideWhat does a water softener cost to run?
Salt, water, power and servicing: where the running costs come from and how to keep them low.
Read the guideWater softeners in Bishop's Stortford
Hard water and softener fitting in Bishop's Stortford.
Read the guideHad enough of
hard water?
Tell us where your stop tap is and send a photo if you can — we'll come back with a fixed quote for fitting a softener.