I have an older house (1955) with an addition that is much newer than the original house by maybe 20 years. When I purchased the house 10 years ago I added a bathroom in the newer part of the house. The water pressure worked fine for a number of years. About 4 years ago I added a couple of new exterior faucets on the older side of the house and the cold water flow on the NEW side of the house, especially in the new bathroom was greatly reduced. For instance in the bath tub the cold water comes out in just a trickle. But if I turned it on hot all the way (I have all single handle faucets) the volume was much higher. At the time I did not notice a water pressure problem except with the bathtub cold water. A few months ago I had problems with the kitchen sink fixture and tested the water pressure. It registered 95. So I had a plumber come out and check and replace the PRV. We only checked a couple of sink faucets in the old part of the house and it was only after he left that I realized that all the cold water pressure in the newer bathroom was extremely low on all fixtures, not just the bathtub. I couldn't take a shower (the water was too hot) in that bathroom and the toilet takes forever to refill and will not even refill at all if the outdoor faucet is on. I retested the water pressure and it is at about 64 PSI on all the outdoor faucets. Another weird (to me) thing is that one faucet on the new side of the house registers 64 PSI but the water flow is MUCH weaker than the other side of the house. I thought it would show a lower water pressure on the gauge. So I plan to ask the plumber to increase the pressure to at least 75 to increase the cold water pressure on that side of the house. The plumber said it would be a lengthy and expensive process to determine what the cause of the different water flows in the new and old sides of the house. Have you ever seen this problem before?