Limescale quietly drives up your energy bills, wears out appliances and forces you to buy more cleaning products. Enter your postcode to see the estimated annual cost of hard water for your household — based on the exact hardness your water company reports for your address.
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Every UK water company publishes the water hardness for each of its supply zones, measured in milligrams of calcium carbonate per litre (mg/L CaCO₃). When you enter your postcode we look up your exact supply zone and its published hardness figure, then estimate what that level of hardness costs a typical household each year across five categories:
| Cost category | Slightly hard ~150 mg/L | Moderately hard ~200 mg/L | Hard ~280 mg/L | Very hard ~350 mg/L |
|---|---|---|---|---|
| Energy waste (boiler inefficiency) | £40 | £80 | £150 | £200 |
| Appliance damage & shorter lifespan | £50 | £100 | £180 | £250 |
| Extra cleaning products | £30 | £70 | £120 | £150 |
| Plumbing maintenance | £15 | £40 | £70 | £100 |
| Extra skin & hair products | £20 | £50 | £80 | £100 |
| Estimated total per year | £155 | £340 | £600 | £800 |
Your result is scaled to your zone's exact mg/L figure rather than a broad band, so two postcodes with different hardness get different results. Just 1 mm of limescale on a heat exchanger reduces boiler efficiency by around 1.6%, and in very hard areas scale can build at roughly 3 mm per year without treatment — which is why energy waste is usually the biggest hidden cost.
Estimates based on published research from the Water Quality Research Foundation, Energy Saving Trust, and consumer surveys. Individual costs vary based on household size, appliance age, and water usage.
These are estimates based on average UK household data and your local water hardness. Actual costs depend on household size, water usage, and appliance age. Hardness data comes from the most recent annual water quality report published by your water company. MyTapWater is independent and does not sell water softeners.