I have a powder room on the first floor and above that is a full bathroom on the second floor. Over the last couple days I noticed that after I flush the powder room toilet, I sometimes hear the upstairs toilet fill for a few seconds (maybe 3-5 seconds). This never happened before the last couple days. Does this indicate a problem? I assume the flushing action downstairs is causing some of the water from upstairs to get sucked out of the toilet. Also, this does not happen every time. Not even every ten times. Though the water level on the upstairs toilet looks a bit low after I flush the downstairs a few times.

Thanks for any help/info!



Edited 1 times.

Check the flapper and fill valve on the upstairs toilet. Either, some of the water has leaked past the flapper and its refilling or the fill valve is borderline ready to fail.

The fill valve in the upstairs toilet has absolutely NO CONNECTION to the flushing of the downstairs toilet. There is a problem in the upstairs tank causing the refilling sound.

Crap I don’t know what I was thinking. I’m a novice but I knew that. Still half asleep when I posted I guess. The fill valve is relatively new so likely the flapper right? I guess it’s just a coincidence that I’ve noticed it happening right after I flush the downstairs toilet.

relatively new fill valve COULD mean the 'refill tube' was NOT installed properly.

put some food coloring into the toilet tank. if there is a slight leak from the flapper, the color will show up in the bowl.

If it is the refill tube, the coloring will STILL enter the bowl