I don't leave it on. After waking up one night to a wet floor (toilet shut off valve failed), I am wary of potential flooding. In fact, I try to remember to turn off city water to the trailer if I'm going to be away for longer periods of time.
Come to think of it, on my last camping trip the couple behind us were bailing water out of their kitchen right after they set up camp. I never asked. It could have been a leaky cooler chest.
There are lots of risks associated with camping. This is one that's just too easy to avoid.
