NEVER, ever, leave the city water on if you are not physically AT the camper and not asleep.
If you ever have a plumbing leak, or leave the tap running unknowingly, you may end up with a massive flood that will total out the rv.
Best bet is to always fill the fresh tank and close off the city water. Use fresh tank and it's pump when you need water.
Turn the fresh pump off when you leave your campsite.
Fresh tank can only run for so long and hopefully would run out before any tanks filled up with a running tap.
...dont ask me how I know.