There are 2 toliets in my building, one one the 1st floor, and the other directly above it on the second floor. When either toilet is flushed, a loud vibration sound is heard from the piping. Should I be concerned?

Toilet loud noise after flushing is caused by a loose washer in the angle valve under the water tank and dirt inside the fill valve.

Close the angle valve half a turn flush the toilet and listen if clears is the washer in at the end of the angle valve stem, if still the same then it can be the fill valve, see the images below and tell me which type of fill valve you have inside the water tank and I will walk you through how to fix your problem, Thanks.

John

How do you fix this? I have the model on the left. THanks!

How do you fix this? I have a model like on the right. Thanks!

Sorry I meant RIGHT!