Sorry, I know this thread is old but just for future readers who might be looking for an answer here... I believe i might have the same tubing installed in the house I just bought as well. I found out it was 3/8" riser tubing I think also called "Swing pipe". A brass 1/2" barbed fitting fits this perfectly, maybe you can adapt it from there.
Hi All, My name is Pete and I just joined the forum. My wife and I bought a house with a (sort of) underground sprinkler system installed. It's really a basic rinky-dink system without any plumbing connected to the main house line or any other professional setup. The whole system consists of the water lines which are just thin-walled 3/8" pipe (i think you pros call it swing pipe) connected to old broken sprinkler heads which i plan to replace. The house-side of these lines just stick up out of ...