Phantom flushes passing the dye test

[Flappergasted]

Hi, I'm a bit confused with a "ghost flushing" problem. I just moved in a new condo (building is only 3 years old) and the toilet is driving me nuts (getting a refill sound every hours or so).

Water level in the tank is lowering leading the flush valve to do its job. The problem is I can't figure out where the leak is coming from since there's no apparent signs of water dripping inside the bowl (did the dye test with a full bottle to be sure, not only a couple of drops and waited 2 hours) nor outside the toilet or on the floor.

Could it be water pressure? One thing to mention, I tried to siphon the bowl for the fun of it and had a burst of water coming out the bathtub tap nearby..

 

[Reach4]

Are you saying that the dye appears in the bowl, or not?

Anyway, I suggest you close the stop valve that supplies the toilet. See at what level the water stops dropping. The most common would be that the water is seeping past the flapper.

 

[Sponsor]

 

[Flappergasted]

Sorry for my english, it's not my native tongue: no, there's no sign of dye in the bowl. I'll try to cut the water and watch for the level.

Edit: nevermind, good thing I let the dye sit an extra hour: I'm getting signs of dye in the bowl now! Should be easier to troubleshoot!

Edit 2: turned out to be the flapper seal (had developed two blisters). It's a Fluidmaster 540 and it seems to be a notorious problem with them according to some other user reviews..