Adding Heads to an Existing Zone: Check Pipe Size First

12 Heads on ½" Pipe Is Impossible—Find the Real Mainline

36 GPM through ½" pipe can’t happen. The ½" pipe likely feeds 1–2 heads off a larger main. Tap into the mainline (1" or larger) for new heads. If pressure is good, you can add 1 head to the ½" branch, but don’t exceed its capacity.