Copper is the preferred material for supply lines in most locales, although flexible or rigid plastic is permitted in some areas. Practice cutting copper pipe and sweating joints before you start. Copper supply lines are usually routed so they do not cross drainpipes or vents. In most cases, it’s easier to make the horizontal runs in the crawlspace or basement. Long runs and bends lower water pressure slightly. Hammer arresters (Step 3) prevent banging noise when you turn off a faucet. Copper pipe is easily punctured or dented, so position it out of harm’s way and install nailing plates to the studs to protect pipes against errant nails. Hot water is always on the left, cold water on the right. Dry-fit a complete assembly for the sink and the toilet. For each stub out, use a tee fitting, a 6-inch length of pipe (which you will cut off later), and a cap to protect the pipe. Install a hammer arrester to each. A drop-ear elbow makes the most secure attachment. If you use one, the hammer arrester must be connected to a tee and an elbow just below the drop-ear elbow. Insert a brass threaded nipple into the elbow.
