Jadnashua
Retired Defense Industry Engineer xxx
5gpm is fine for many things, so no, 1/2" pipe is not the issue. As said, you have a restriction somewhere. Hard to say where without some on-site investigation. Now, it would help if we knew the size of the main water line into the house and the size of the water meter.
When the pressure drops radically when you open a valve, it's a supply problem...not enough supply for whatever reason.
When the pressure drops radically when you open a valve, it's a supply problem...not enough supply for whatever reason.