We own a two-story home (plus a full-basement) that was built in 1995. We've lived in the home for the past 7 years, but we've noticed this problem in the last two years.

If we are running water in the bathtub on the second floor and we flush another toilet on the second floor at the same time, we hear a relatively loud groaning sound for 3-4 seconds.

And idea what is causing this noise?

Should we be avoiding flushing the toilet while running the bath? (FYI: this would be rather inconvenient, as we have two toddlers so we take a lot of baths and there is a rather substantial need to flush the toilet while the bath water is running).


I am hoping to get a response to this e-mail. I realize that a full diagnosis is probably going to be difficult, but a few ideas of what could be the problem would be helpful.

Thanks in advance. Y'all are the best!

My guess is that bthe sound you hear is coming from the ballcock. Which one is yours. (see images). Let me kinow, Tom

Sorry for the slow reply (it's been really busy).

I don't think the toilet is the location of the noise (this is new information).

Here's why: Last night, I flushed the toilet in the basement after the bath had finished running. Just as the tank of the toilet finished filling, I heard the noise again and it was definitely coming from upstairs.

It's almost like air is getting in the supply lines or something like that and it's belching out.

FYI: The basement toilet is like the one on the left; the other toilets are like the one on the right.