Check out some similar questions!

ovexi · Jan 7, 2008, 08:55 PM

After I flush the toilet and the water went down the drain, a few moments later I hear a loud banging noise from the basement. I did some reading and it is suggested that I may have a water hammer. However the water hammer is normally associated with a closing valve which is not the case here. The toilet valve closes after the tank is full. I am thinking that it may be related to the drainage pipe rather that the water supply pipe.
Thank you for any help.

ballengerb1 · Jan 8, 2008, 02:15 PM

So you are saying that you are 100% sure the bang does not coincide with the fill valve stopping the supply to the tank, right? There is a chance that your drain pipe is lossely supported and the waste water slams into a 90 turn causing a bang but I think that would happen before the fill valve shuts off. Can you give us a time line in sceonds from the flush to the bang to the fill valve closing?

ovexi · Jan 9, 2008, 09:11 AM

It's probably 1 second since the tank water went down the drain and the bang noise happens. I hear the bang before the valve shuts off so it is not likely water hammer.
And what makes the diagnose even harder is that the basement is finished so I have no access to the drain pipe unless I break the wall.

ballengerb1 · Jan 9, 2008, 09:30 AM

It does sound like the waste water is slamming into a turn in the drain but you are stuck without being able to get into the wall. Maybe someone else will jump in with additional thoughts.

ovexi · Jan 9, 2008, 10:34 AM

Originally Posted by ballengerb1

It does sound like the waste water is slamming into a turn in the drain but you are stuck without being able to get into the wall. Maybe someone else will jump in with additional thoughts.

Yes, that is my feeling too. The question is how long can I live with this? Do I need an emergency repair? Am I going to get a flood soon?

ballengerb1 · Jan 9, 2008, 01:41 PM

If it is what I picture it isn't likely to cause a leak. Will you get used to it, probably not because you are always going to want to get to that fix it part of the problem.

ovexi · Jan 9, 2008, 03:09 PM

Originally Posted by ballengerb1

If it is what I picture it isn't likely to cause a leak. Will you get used to it, probably not because you are always going to want to get to that fix it part of the problem.

Thank you bellengerb1. I really appreciate your help. However, what does seem to be the problem? Why I developed this noise?

ballengerb1 · Jan 9, 2008, 03:27 PM

It is possible that the pipe hangers that held the drain pipe have loosened over time. That could allow the pipe to move evn just 1/8" enough to make a thump againist the floor joists.