The plumbing in my house is circa 1989. The hot water line comes from the heater and runs to the kitchen, master bath and then up to the upstairs bath. Same for the cold water line, except it comes directly from the pressure tank. So, when you use any cold water…even if its upstairs at the end of the line, you will get scolded by the hot water due to the pressure drop in cold. I know, I know, lower the water temp so you don’t get scolded. Besides that, what can I do to keep this from happening? I added a basement bathroom to a house in Colorado. Ran the hot and cold water directly to the bathroom from the lines coming from the two sources. Never had a problem with pressure…even if I flushed the toilet in the new basement bath at the same time as the shower. The only difference I can tell is that the Colorado house has municipal water supply and the current house has a well. I can do basic plumbing so sometimes the more advance issues I need help on.