Five reliable ways to find out how hard your water is — from free online tools to laboratory-grade accuracy.
The quickest way to find your water hardness is to enter your postcode on our homepage. We use data from UK water companies to show the hardness level for your supply area, measured in ppm (parts per million of calcium carbonate).
This gives you a reliable baseline. Water company data reflects the average hardness at the treatment works supplying your area. Actual hardness at your tap may vary slightly depending on your local pipework.
Test strips are the most popular physical method. Dip a strip in a glass of cold tap water for a few seconds, then compare the colour change against the chart provided. Results in under a minute.
150 test strips with easy-to-read colour chart. Tests from 0-425 ppm. Fast results in seconds. Ideal for checking tap water hardness or verifying your water softener is working.
View on AmazonA TDS (Total Dissolved Solids) meter measures the total mineral content of water, displayed as a ppm reading. While TDS is not exactly the same as hardness (it includes all dissolved minerals, not just calcium and magnesium), it provides a useful approximation.
A simple but unscientific test. Fill a clear bottle one-third with tap water, add a few drops of liquid soap (not detergent), and shake vigorously.
This won't give you a ppm reading, but it's a quick way to confirm whether your water is noticeably hard.
Every UK water company publishes water quality data for its supply areas. You can usually find your hardness level by entering your postcode on their website, or by calling their customer service line. They report hardness in ppm, Clark degrees, or German degrees (dH).
To understand what these numbers mean, see our guide on what water hardness is and how it's measured.
| Method | Cost | Accuracy | Speed | Best For |
|---|---|---|---|---|
| WaterHard.uk postcode | Free | Good | Instant | Quick baseline check |
| Test strips | £5-10 | Good | 1 minute | Physical confirmation |
| Digital TDS meter | £8-15 | Moderate | 10 seconds | Ongoing monitoring |
| Soap test | Free | Low | 1 minute | Rough indication |
| Water company data | Free | High | 5-10 minutes | Official figures |
Once you've established your water hardness, the next step depends on the result:
Check your postcode now for a free instant result, or explore solutions for hard water.
If you want physical test equipment on hand, here are the most reliable options:
3-in-1 meter measures TDS, EC, and temperature in seconds. Good ongoing-monitoring tool — perfect for checking before/after a softener install or shower filter. Auto-calibration. Takes two button batteries (included).
View on AmazonProfessional-grade strips measuring total hardness, chlorine, alkalinity, pH, and iron. More detailed than basic strips — good for aquariums, water softener owners, and anyone on private supply.
View on AmazonLiquid titration kit — the most accurate home option. Measures calcium + magnesium hardness directly (not TDS). Lab-style test, ~60 uses per kit. Popular with water softener engineers for verifying installs.
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