Gemma
All professional drive through car washes use pure water for thier final rinse, we wash all the vans weekly with pure water, even our Fiats and Renault Trafic
!!
I think I have about 8769 washes left on it before it falls to bit's.
Ewan, Hope you're not driving a Transit as that'll be a rust bucket after driving through a small puddle never mind actually risking washing it. That's why you see so many filthy builders Transits, they're too scared to wash them!