Loud Toilet Flush

When I flush my toilet, I hear a loud noise throughout the house. What is it?

This is a real question that I've seen come up many times:

Q.

> Hi.
> 
> I have a noise problem with my plumbing and i'm hopeing that someone out
> there can give me some advice.
> 
> My problem is this. Every time I flush the upstairs toilet there is a loud
> rumbling noise all throughout the house. This doesn't happen if I flush the
> toilet downstairs.
> 
> Anyone know what's going on?
> 
> TIA.
>

A.

If the rumbling noise is more like a 'bang' and rumble that happens when the toilet finishes filling its tank, then the issue is water hammer. The symptom can be solved sometimes by replacing the toilet fill valve with a different kind, but the real cause is usually a bad (or missing) expansion tank. The expansion tank is installed at the water entrance if on a private well/spring system or near the hot water tank, usually, if you are on a public supply. You may also notice your hot water heater will 'blow off' if the expansion tank is bad (or not installed at all). In some cases, small hammer arrestors may need to be installed on the top floor under a lav sink. Most (good) plumbers install these behind the wall with the shower valve, but they tend to fill up over time and loose their shock absorbing capacity until someone drains that branch down well enough to recharge the air in them.

If the rumble happens as soon as you flush the toilet, it means that the drainage pipe may be loose in the floor and wall. In high end work, I like to use cast iron in the wall for 2/3rd story drops because it's quieter. The PVC used most comonly can be noisy even if it is well secured. Check for hangers every 4 feet in the basement if the pipe is exposed. You may need to open some walls/ceilings to fix it.