I bought a house 2 years ago that was built in 1958. Had galvanized plumbing when I moved in and it was almost completely sealed off with rust. I had all the plumbing from the main line replaced a week after moving in. My water pressure is great with just one item on but drops drastically with more than 1 item one. I bought a water pressure gauge and installed in on the bib where the main line comes in from the street and my pressure is 78 PSI, so I know that I have great pressure. They did not install a PRV when they put in the Pex pipe throughout the house. Is there something else I can test, should I test on my cold water hook up for my washer which is the furthest away from my main line? Is there amything I can do to have a more steady pressure?