Here is the inside of our toilet tank:
Not sure what that "yellow thing" on the top is, but I believe that's the main culprit to focus on. For now, I'll call it the yellow thing.
When the water supply is running full bore, water seems to be leaking out of the top of that yellow thing, where the "cap" (or whatever it is) is. This causes the toilet to sound like its "running continuously", or refilling continuously. Meaning, its never quiet and just constantly makes that sound that a toilet makes when its tank is refilling with water.
So a few days ago I shut off that water supply line, just because the running noise was driving us crazy and I didn't really have any time to look into the issue.
Despite the fact that I shut the water supply off, we've still been able to use the toilet in those last few days! Not sure if that's normal, but is not what I was expecting! However, as you can see, the water line is pretty low. So perhaps we just haven't flushed it enough times (since it's been turned off) to fully drain it.
But now that the water supply line is shut off, and the water in the tank is low, the bottom of that yellow thing drips constantly and is driving us crazy.
Clearly we have at least 1 leak here. I'm worried that we have a leak not only in that yellow thing (again, whatever it is) but perhaps also in our water supply line valve. How else would water be constantly dripping into the tank when the supply line is shut off?
Either way, any ideas as to what is going on here and how to fix our toilet? The desired end result is normal toilet functioning, with the supply line turned off and with it not "running continuously". Thanks in advance!