Why it matters
Hard water areas in particular cause scale to build up inside the heater's tank, reducing how efficiently it heats and, over time, straining the heating element.
How to do it
- Follow the manufacturer's specific descaling instructions for your unit (Truma and Whale differ slightly).
- Drain the tank fully and, where recommended, run a descaling solution through before flushing thoroughly with fresh water.
- Check the anode rod (where fitted) at the same time and replace if significantly worn.
How often
Once a year, more often in known hard-water areas.
Rough UK cost
£10 - £30 for descaling solution and an anode rod, if DIY; £60 - £120 if done professionally.