Can PEX be used for the trunk

Question

Currently I have a length of galvanized steel pipe (3/4") from the water meter, which is feeding the main trunk (3/4" copper). The water pressure in the house is very low, and I suspect it is due to restrictive buildup in the galvanized pipe.

I have enough 3/4 PEX left over from another project, but was wondering if I can replace the galvanized pipe with PEX (from a code compliance stand point)?

In most PEX systems that I've seen, the manifold is fed by copper. So I'm not sure if there are some codes that prevent PEX from being connected to the water main, or if there is some other reason this is done.

I would like to avoid buying copper pipe if I can, since I already have the PEX. I live in New York (the state, not the city).

Answer 1

I have seen PEX used in this application. I also see PVC feed lines for Water supply in many jobs. As far as PEX, brands my differ a little, but the standard is 100psi at 180F 160psi at 74F. Most public water supplies range around 50 to 70 PSI, and this is cold water. Check local codes, but I think you will be fine with proper connectors.

Answer 2

In California a special kind of PEX (foil lined?) is required for in ground service to prevent any chance of chemical leaching. Obviously a NY resident is not bound by CA code but you may wish to consider if the reasoning makes sense to you.

On the other hand, PVC is allowed for a water main and PVC is pretty cheap. Since you are concerned about water pressure, why not upgrade to 1.25" PVC pipe. Just make sure it's CL200 or better.