When my upstairs showers are turned off, the supply line to the toilet on the 1st floor vibrates really loud. Could it be water hammering?

I did put food coloring in the tank overnight to see if my flapper was leaking..no leak.

Also, seems like the momentum of this water exerts enough force to push the toilet valve open momentarily.

Any thoughts on what to change first on the toilet? Fill valve in toilet or shut off valve?



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close the shutoff under the toilet. make sure it is shutting off 100%.
now open/close the shower valve.
what happens ?

With the valve off, there are not vibrations or hammering. I can now make the problem occur all the time.

I changed the flush valve, shut off valve and supply line. Shut off valve was 15 years old and had a small leak once I turned it back on.

Seemed the culprit was a bad seal on the flush valve. I have not had the issue since making the changes.

Thanks for the assistance.



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