Every RV owner should be using a water pressure regulator on his city water supply to protect the water system from excessive water pressures. The reason is that RV water systems are designed for low pressures and are normally designed to operate at pressures less than 60#. Many cities have water pressure that is far above that and that could cause serious damage to your plumbing system. The standard answer to this problem has been the use of a water pressure regulator that is purchased from your local RV store. There are several types available ranging from cheap plastic to brass ones and some also have pressure gauges and priced from $5 to $10. There is also an adjustable one that will cost about $35. But none of these are the complete answer to supplying enough water, while still protecting the plumbing systems.
While these regulators do protect the RV water system from excessively high inlet pressures, they are not a total answer. And it has been my experience that the adjustable regulator from Marshall Brass that is sold at the RV supply stores is very little better. The reason is that while these products limit pressure they also limit the volume of water so much that the pressure supplied drops by 10# or more as soon as one begins to use water. The answer is to replace your pressure regulator with one of the "whole house" regulators from a plumbing supply house. I used one by Watts Regulators. (model N45B)
You can get one from most Home Depot stores or from Lowe's. If it is not available from one of these, any plumbing shop should also have them. They are available in either 1/2" or 3/4" flow sizes. I used the 3/4" size for best supply. You will also need a female hose bib for the inlet side and a male bib for the outlet and some teflon tape to seal the connections. You will also need a pressure gauge to adjust the operation pressure of the supply. I used one that is available at most RV supply stores and I attached it to the connection where the water enters the RV so that it shows the pressure down stream of the supply hose. With this system we now have showers and a sink sprayer that work just as well as the ones in a stick built home. The only question that I still have is why it took me so long to get around to doing this. One other suggestion is that you use one of the brass "Y" adapters when you hook up to the water hydrant to allow you to have another hose connected at the same time.