Advice
Hard water in London and Hertfordshire: what limescale does to your home
By Urgent Plumbers London team4 min read
In short
Hard water carries dissolved calcium and magnesium. When it's heated, they form limescale on boiler heat exchangers, immersion elements, taps and shower heads. That cuts efficiency and causes early failures. Scale reducers, sensible temperatures and regular cleaning all help.
If you've ever descaled a kettle in London or Hertfordshire, you've seen limescale. The same build-up happens inside your boiler, hot water cylinder, immersion heater and shower, where you can't see it.
What causes limescale?
Hard water contains dissolved minerals, mainly calcium and magnesium, picked up as rainwater passes through chalk and limestone. Much of London and Hertfordshire's water comes from those rocks. When hard water is heated, the minerals come out of solution and stick to hot surfaces as limescale.
What limescale does
- Coats immersion heater elements, making them overheat and fail early
- Builds up in a combi boiler's heat exchanger, causing kettling (banging and whistling) and lower efficiency
- Blocks shower heads and aerators, reducing flow
- Stiffens taps and valves
- Reduces the efficiency of hot water cylinders
How to reduce the damage
- Fit a scale reducer. Building Regulations guidance expects limescale protection on new boiler installations in hard-water areas
- Don't run hot water hotter than it needs to be: 60°C is right for stored hot water
- Descale shower heads and tap aerators regularly with vinegar or a descaler
- Consider a water softener for the whole house (keep a hard-water tap for drinking)
- Have heating systems power flushed if sludge and scale are causing cold spots
Is hard water safe to drink?
Yes. Hard water is safe to drink, and the minerals in it aren't harmful. The problems are with appliances and heating, not health. If you fit a water softener, it's usual to keep one unsoftened tap in the kitchen for drinking water.
