Water Line Fittings PEX is quickly becoming the material of choice for water lines. But PVC, CPVC and copper are still in common use, as is galvanized steel outdoors.

You can run PEX line as you would in a conventional plumbing system, with 3/4-in. main lines and 1/2-in. branch lines. You can also use a “manifold” system, where you run a 1/2-in. line to ...