How to Test Water Hardness at Home

1. Use the WaterHard.uk Postcode Checker (Free, Instant)

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.

2. Water Hardness Test Strips

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.

• Accuracy: Within 25-50 ppm — good enough for most purposes
• Cost: £5-10 for a pack of 50-150 strips
• Best for: Quick confirmation of hardness level, testing after softener installation

3. Digital TDS Meter

A 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.

• Accuracy: Good for relative comparisons; less specific than hardness-only tests
• Cost: £8-15 for a basic digital meter
• Best for: Ongoing monitoring, comparing before and after water softener installation

4. The Soap Test

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.

• Lots of bubbles, clear water below: Your water is soft
• Few bubbles, milky/cloudy water: Your water is hard

This won't give you a ppm reading, but it's a quick way to confirm whether your water is noticeably hard.

5. Water Company Reports

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.

Comparing Test Methods

What to Do Once You Know

Once you've established your water hardness, the next step depends on the result:

• Soft (0-60 ppm): No action needed. You're unlikely to experience limescale issues
• Moderate (61-180 ppm): Regular descaling of kettles and appliances is usually sufficient
• Hard (181-300 ppm): Consider a scale inhibitor for your boiler and a shower filter for skin/hair benefits
• Very Hard (301+ ppm): A water softener is the most cost-effective long-term solution

Check your postcode now for a free instant result, or explore solutions for hard water.

Best Water Testing Kits for UK Homes

If you want physical test equipment on hand, here are the most reliable options: