The metal utility water line has always been a neutral path, whether the PoCo neutral is connected or not. Remember current doesn't take the path of least resistance, it takes all paths. The copper water pipe may end up having more circular mils and lower resistance than the 1350 aluminum conductor. Back in the olden days the whole water system was a grounded conductor. This is nothing new. What is new is that water pipe is probably plastic now. That will certainly be true soon if the original was lead.
