Hi All, I have a Hunter sprinkler system. The outside pipe above the backflow valve is pvc. Every year a small section bulges and cracks. The repairman who fixed the first time said the 1/4 turn ball shutoff valve inside might be leaking. After the second time it cracked I cut the pipe out myself. There was no moisture inside. The shutoff valve is not leaking. I am assuming the crack is caused by water getting in somehow. I have system winterized every year. Could there be a problem with the backflow valve? Thanks!