Every now and then my upstairs sink, bathtub and toilet will sputter when the water flows. Cold or hot, doesn't matter. It acts as if I had turned off the main and opened a valve and allowed air in the system, which of course I haven't. I've looked everywhere for leaks, but even if there was a hidden leak, I would think that that would be the source of air getting into the system. Any ideas?
Thanks in advance
Rp