: We have a 20's house that has had some replumbing, but the pipes in the basement are galvanized. At one point, there was a new supply brought in from the street. For the most part, water pressure is good in the house (we are on Seattle City Water system), but when more than one faucet is open (or toilet flushed, etc), the pressure drop alot.

: For the most part it isn't a big deal except if someone is in the shower. I understand that we can probably get a lot of this condition fixed by having the horizontal pipes replaced in the basement. Eventually, we'd want to do most of the others, but don't want to incur that kind of expense yet.

: Is the new PEX good? Or should it be done with Copper?

Mike,
The new PEX is good, in some cases, better than using copper. It's what I would use in my home, with some copper near the valves where stiffness is needed.

As far as replacing some pipes and leaving others, it depends on how much time you would spend without knowing whether you had "nailed" the problem.
It's kind of like the phrase, "It's in the last place I looked."
You could fix it with one piece of pipe section, or it could be the last one you replace.
A plumber would look at this as a "trial and error" method of helping the homeowner. It leaves the whole thing "open-ended".
Mixing galavanized and copper is not good.
I don't recommend leaving any in once copper is being added.
At the time a repipe is being done, a nice idea would be to add an expansion tank to the system.
Terry

• Piping information