First, thanks for the wonderful forum!

Second, we have been experiencing a soft bang or creak in our pipe when we flush the toilet. It doesn't happen every time we flush, maybe once or twice a day, and while the toilet is still filling up with water, so I do not believe it is water hammer. It seems to be where the water starts to go downward instead of across. I know very little about plumbing, but is there some type of valve or flap that opens and closes when water changes direction? Our pipes are very noisy in that area to begin with, we can hear the water rushing through them quite well. It has been doing this since we moved in about 2 years ago. Could it be the normal noises pipes make(hopefully)? Or is it something that we should get checked out? Thanks!

Our rule of thumb on the apartments:

When pipe noise occurs with toilet flushing, we replace the flush valve. It ends the problem 9 of 10 times.

We use and prefer the Fluidmaster 400A.

First, thanks for the wonderful forum!

Second, we have been experiencing a soft bang or creak in our pipe when we flush the toilet. It doesn't happen everytime we flush, maybe once or twice a day, and while the toilet is still filling up with water, so I do not believe it is water hammer. It seems to be where the water starts to go downward instead of across. I know very little about plumbing, but is there some type of valve or flap that opens and closes when water changes direction? Our pipes are very noisy in that area to begin with, we can hear the water rushing through them quite well. It has been doing this since we moved in about 2 years ago. Could it be the normal noises pipes make(hopefully)? Or is it something that we should get checked out? Thanks!
You're correct, it isn't water hammer. I'm starting to get complaints of pipes creaking, popping, and growling inside walls. As it gets warmer and more people kick on the AC there's a temperature difference between room temperature and the temperature in side those walls. The pipes strapped to the studs and floor joists begain to contract and expand as water runs through. To get specific I'd have to be at your place but that's the most common cause of pipe noise that there is. The pipe expands and pops. Later it contracts and squeeks. Thereis no valve that opens or closes when water changes direction. If you have PVC or ABS plastic pipes you will hear more noise then if you had cast iron. I haven't helped much but I hope I've taken some of the mystery out of it. Regards, Tom

Rickj, it's actually a house, but we had a ton of problems already with the flapper leaking. So I'll definitely look into getting the fluidmaster since we need to replace it anyway.

Speedball, I'm glad that you could confirm it isn't water hammer. So, it doesn't sound like anything serious. I think you are correct because it does seem less noticeable in the winter & our pipes are PVC. We'll just be sure to watch for any leaks. Thanks again!

If the flapper is leaking, just get the valve that has a flapper with it.

I agree that the sound could be these other things, but the investment of under $10 for a new valve and flapper is a good one... and if it does cure the pipe sound, then that's just a bonus.