Moderator Post (s) for this thread: >Not airbyBillhart on 03/20/2007
* The valve that fills the toilet bowl after a flush could be defective.
* It reacts to water pressure changes, it will flutter and cause a banging sound.
* Sometimes just turning on a shower will cause this condition.
* Shut off the water supply at the toilets. If the condition goes away, turn on the water at the toilets one by one until you find the bad one. Replace the defective valve.
* Good luck... Adios... Jasper...