can the city water run into the trailer at all times?

Unlike others, I have never used a regulator in 25 years and only turned off the water when we were seasonal and going home for the week. Also never use the pump or fresh water tank except for sanitizing and winterizing.

Once hooked up and water is on, do you hear it running? If you are not running the faucets then there should not be any water in your holding tanks. Look uphill from the wet carpet for the leak. Good luck.