I'm glad you solved your problem, but I'll relate a similar sounding noise problem and solution in case it helps others.
I had a relatively new house, and the bathroom that was seldom used had something that sounded like water hammer or an interruption in the flow of water to the toilet. I'm not sure why I did this at the time (and it was nothing I would have been logically thinking to do - except possibly the source of the sound or vibration maybe), but I disconnected the fill hose to the toilet. The toilet Fill pipe had some type of ball at the end of the pipe that connected to the shutoff knob. That ball had 3 slots through it for the water to pass to the toilet. As it turns out, there were pieces of solder in there that were clogging those 3 slots. When the water flowed, they clogged the holes, releasing the pressure, then fell back down, some more water flowed, and the process repeated till the toilet tank was filled. Removing the solder pieces solved the problem.
Come to think of it, I believe my kitchen faucet had a bad flow due to solder pieces in the aerator as well in those early years of the house.
So the basic rule, I guess, is to clean out your pipes where you can for construction junk. I know the water (at least now, and probably then as well) is pretty well-controlled municipal water (
MWRA-The MWRA recently completed a new aqueduct and various water processing facilities on time and on budget, unlike our "Boston Big Dig"), so it is not water chemistry dissolving the solder joints.
Hope this helps someone.
Regards,
Ira