We are the first owners of the house which was built in 2000. The water pressure to the house is very good. Until about six months ago, the water press was good with multiple faucets, dishwashers, clothes washer running. But now the pressure is good until a second device using water (faucet, shower, dish washer - anything) is turned on. Then the water is reduced to a dribble. I suspected the pressure regulator at the point of entry for the water line and had a new one put in, but that didn't solve the problem. I don't have a water softener. Any ideas of where to look next?

This is a volume problem. If your houde had galvanized pipes and was older I'd know right away. The pipes had so much minerals built up in pipe walls that it restricted the flow. But that's not the case here. Something's restricting the flow and the first place I would look is that PRV valve. You could have a bad new one you know. Or, when you changed it out something in the service could have got into the valves opening blocking the flow. In any respect that's where I would start checking. Good luck, Tom

Are the valves open completely? Has there been any water line repairs done recently? Does your water meter move when no water is turned on?