This could be one that I could help with from experience.
When you arrive at your van do you.
1. Use a water butt
2. Connect dirrect to the mains.
1A Wash out barell
2B Allow water to pass to waste for at least 2 minutes, this will allow all standing water to be flushed.
3. Boil the kettle once, use water for the bowl for after.
3A Boil water in the kettle for the second time to over come
the problem of a standing kettle.
4. Use an inline cartridge filter on your hose pipe available
e.bay or a Koi carp dealer.
Note 2B & 3A worked for me, no comlaints about the tea now