Hi all - I've been trying to diagnose for over a week now an issue with vibrating pipes while a toilet re-fills after a flush. The vibration doesn't last the entire time the toilet is filling - starts a couple seconds into it, and stops a few seconds before the tank is full.

We have a total of four toilets around the house, and all four cause post-flush :-) vibration to some degree. Our water is supplied by the city, if that matters. The house is about 6 years old, and the toilets and plumbing are all original.

- I've read that these things are usually caused by a failing ballcock, so I've actually replaced the ballcocks in two of the four toilets with Fluidmaster ones, but still have the problem.

- Instead of replacing the ballcocks in the other two toilets, I shut-off the their respective water supply valves to see if the problem went away. It didn't. QUESTION: Was this a valid test, and can I eliminate the ballcocks in those two toilets as the culprit?

- Assuming I eliminate all four toilets as problematic (by either replacing their ballcocks, or shutting off their water supply valves), can there be something else that could be causing this? Could it be a leaky faucet? I don't have any that I've noticed. Could it basically be anything that's attached to the cold water plumbing (water heater?, dishwasher?), even though they are not currently taking any water?

I'd very much appreciate any other pointers in diagnosing the problem. Unfortunately, since the vibrations only last for a few seconds, it's tough to do a series of tests while the vibrations are happening.

Thanks!

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