I have a water meter with a 3/4" supply line that is fitted to an adaptor which then runs 1/2" to all the pipes in my house. I'm in the process of installing a PEX manifold system for some new connections and I'm wondering if there's any reason I shouldn't remove the old adaptor and just run 3/4" from the main supply to my manifold. It seems silly to leave it as is while I'm doing the other work.

The manifold has a 3/4" PEX input with 1/2" outbound PEX connectors on valves.

For what its worth, the plan is to then run one of the outputs from the manifold to the existing 1/2" copper pipe to supply the lines that aren't being added. All pipes in question are exposed and easy to access in the basement.

  • 2
    You're right--that would be silly. Ludicrous, even. Your plan seems solid.
    – isherwood
    Jul 26, 2016 at 19:54

1 Answer 1


Is the manifold 3/4? If you have easy access to do it, then you are correct that now is the time to do it.

  • 3
    3/4" will provide more flow with less pressure drop than the 1/2" agree with longneck.
    – Ed Beal
    Jul 26, 2016 at 18:53
  • @EdBeal Is there a chance that the increased flow will increase the wear on the existing copper elbows to a significant degree? Jul 26, 2016 at 20:58

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