Why it matters
Frozen water expands and can crack tanks, pipes and the water heater; a flat leisure battery over winter can be permanently damaged; and a sealed-up, damp van is an invitation for mould.
How to do it
- Drain the fresh tank, waste tank, water heater and all pipework fully - use the low-point drains and, if unsure, an airline to blow the system through.
- Add antifreeze-rated protection to the toilet system where applicable.
- Disconnect or trickle-charge the leisure and starter batteries so they don't sit flat all winter.
- Leave roof vents slightly open (or use a dehumidifier) to reduce condensation build-up inside.
How often
Once, before the first hard frost of the season, and reverse the process fully before first use in spring.
Rough UK cost
Free if done yourself; £60 - £150 if a garage winterises it for you.