I've used city water for years and have never had an issue. It should be a non-issue if you use common sense and are properly prepared vs worrying that the worst is going to happen.
1. I always turn off city water when I am outside of the coach.
1a. I always shut off the water pump when I'm not on city water and I'm not inside the coach because you can still pump out 50 gallons of water into the coach..... and 50 gallons of water will do as much damage as 500 gallons. At least with city water someone may see the water pouring out of the coach and run over and shut off the city water for you. If your coach is locked and the pump starts running, the water won't stop until the fresh tank is dry. And I do carry a spare water pump.
2. I always use a pressure regulator with a gauge..... and I always carry a spare.
3. If the coach plumbing does not come with a quarter-turn shutoff valve for the toilet, I always install one in case the flush valve fails. This way you can still use the toilet until you can get it fixed by turning the water on and off at the toilet.
Its not rocket science..... its common sense...... and this thread is almost bordering on the threads where people post they won't flush toilet paper into their black tank!