3 easy ways to find out how hard your water is

So, you know you’ve got hard water — your kettle’s crusty, your shower screen is cloudy, and your soap just doesn't get soapy. But just how hard is your water?

Knowing your exact water hardness isn’t just a nice to know — it helps you choose the right products, protect your appliances, and deal with limescale before it builds into a bigger (and more expensive) problem.

The good news? You don’t need a lab coat or chemistry degree to find out. Here’s how to check your water hardness at home, quickly and easily.

1. Check your local water supplier's website

Most water suppliers in the UK offer a postcode checker or water quality report online — and it’s usually free and straightforward to use.

If you already know your supplier, head to their website and search for “water hardness.” Not sure who supplies your water? Just type “who is my water supplier in [your town or postcode]” into Google and you’ll find it in no time.

For example, if you’re in Poole or Bournemouth, Bournemouth Water’s checker tells us the total hardness level in Alderney South is 96.02 mg/L as calcium.

But what does that actually mean?

That number refers to the concentration of calcium carbonate (CaCO₃) in your water — which is how water hardness is usually measured in the UK. And here’s where it gets useful:

According to the Drinking Water Inspectorate (DWI), water hardness levels are classified like this:

Soft: up to 100 mg/L

Slightly hard: 100–150 mg/L

Moderately hard: 150–200 mg/L

Hard: 200–300 mg/L

Very hard: over 300 mg/L

So in the example above, a reading of 96 mg/L means your water is just about in the soft range. Lucky you (and your kettle).

2. Online Water Hardness Checkers

A few water softening and filtering brands also offer postcode-based tools on their websites. These can be handy if you’re browsing for products or just want a second opinion — but bear in mind that they don’t always show where they get their data from, so take it with a pinch of (calcium-rich) salt.

Still, they’re worth a look:

Harvey Water Softeners

Phox Water

3. Use Hard Water Test Strips

If you want a hands-on test of the water that’s actually coming out of your tap, grab a pack of hard water test strips. They’re cheap, quick to use, and easy to find online or at your local DIY store.

How they work:

You dip the strip into a small glass of water for a few seconds, then compare the colour change to the chart included in the packet. This gives you a direct reading of your water hardness in mg/L.

They’re great for checking your home water — especially if you want to compare results from your kitchen tap, your bathroom, or even before and after installing a filter.

We’ll be reviewing the most accurate and easy-to-use test strips soon — so keep an eye out.

Limescale Lowdown (Key Takeaways)

Hard water = high levels of calcium and magnesium — and yes, that’s what’s behind the limescale in your kettle, pipes, and shower.

You can easily test your water at home using a supplier or water product website’s postcode checker or using at home test strips

Knowing your water’s hardness helps you choose the best solutions — from vinegar descaling to full-on softeners.