So I am about to replumb my house. From the meter to my house is 3/4" 60 yr old galvanized pipe. Once it gets to the house it changed to 1/2" lines serving everything in the house. Example is a 1/2" supply to each fixture branching off of a 1/2" line. I have 82psi inside the house. When I use two fixtures like toilet and washing machine pressure drops to 12psi. I measure this with a water pressure gauge on the water hose bib.

I plan on replacing the 3/4" galvanized to 3/4" pex and run all my fixtures with separate 1/2" lines to each fixture attached to a 3/4" pex manifold. i am using Expandable Pex A so that i wont lose ID in the fittings. i am also will use a pressure reducer to keep pressure at 60psi.

Does anyone for see any problems with this upgrade?

  • You wouldn't expect pressure to remain high in an open system, would you?
    – isherwood
    Jan 26, 2019 at 16:32
  • I have no clue what you are asking me. Jan 26, 2019 at 17:52

1 Answer 1


I see your system design viable and acceptable, however modern practice would dictate 1" main lines, 3/4" sub-lines and 1/2" branch to individual fixtures. I would run 1" to the manifold. Depending on the individual length, 3/4" and 1/2" would be run to the fixtures.

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