Hi and welcome to the forum.
Sorry for your troubles. High water pressure can cause some real problems if the coach isn't protected by a regulator.
On many RVs... there are two connections between the city water and the fresh water tank. The first is a backflow prevent valve and the second is the valve which determines if you're using city water or filling your fresh water tank. Those are two places to look but you'll just have to follow the lines to track down and fix the problem.
BTW, it will help you get more accurate answers if you add the year, make and model of your rig in your signature line. You can do that via the User Control Panel (User CP).
Best of luck finding the problem and please consider buying a pressure regulator.