Type in your postcode and we'll show the hardness of your mains supply in parts per million (ppm), in Clarke and German degrees, the soft-to-very-hard band, your water company, and a plain recommendation. The figure that matters is ppm of calcium carbonate: above roughly 200 ppm you're in hard-water country, and most of southern and eastern England sits well above that.
Check your water hardness
Enter your UK postcode, or just the first part (the outward code, e.g. SW1 or M14). We match it to your water company's published supply data.
We only read the letters and first digit of your postcode. Nothing is sent anywhere; the lookup runs in your browser.
Figures are representative averages for each water company's supply zone, drawn from published water-company hardness data and the UK Drinking Water Inspectorate classification. Hardness can vary within a region because companies blend several sources, so for an exact number for your street, check your water company's own postcode tool or ask for a hardness figure on your bill. This tool is guidance, not a lab test.