Hard vs soft water

Every home's water sits somewhere on a hardness scale, and where it sits shapes everything from your kettle's lifespan to how much soap you need.

What makes water "hard"?

Hard water has picked up dissolved minerals, mainly calcium and magnesium, as it passes through rock like limestone and chalk. Soft water has few or none of these minerals, either naturally (in areas with granite or clay bedrock) or because it's been treated.

How do I know which I have?

Water hardness is usually reported in mg/L of calcium carbonate, or in “degrees” (°Clark, °dH). It varies by region and even by street, since it depends on local geology and your water supplier. UK water suppliers publish hardness by postcode; use the checker above for a quick estimate.

Signs you have hard water

Limescale buildup around taps and shower heads, soap that doesn't lather easily, a white film on dishes and glassware, and dry skin or dull hair after washing.

Signs you have soft water

Water that lathers quickly with less soap, few or no white mineral deposits, but potentially more slippery-feeling water (some people find it takes getting used to).

Does hardness affect health?

Hard water is generally safe to drink, since the minerals it carries are the same ones found in food. The main downsides are practical: appliance wear, cleaning effort, and energy use.

Can I change it?

A water softener swaps calcium and magnesium for sodium or potassium via ion exchange, producing consistently soft water throughout the home. It's the most common fix for genuinely hard-water areas.