Toilet constantly making a noise

Question

https://youtu.be/sI0OCBpdwXk

For the last little while my toilet has been constantly been making a noise as you can hear in the video. I looked it up and it seems like there are two common causes of noise. It seems like the float and fill valve are working as intended. And I thought the flapper was okay since I applied pressure on top of it and it didn't affect the noise at all.

But I tried closing the intake valve for my toilet tank and the tank has been slowly draining. What is likely causing the leak? The water in the bowl seems still, not like there is a steady source of leaking into it? Any advice would be appreciated!

Edit: Thanks for the help everyone. The food colouring test helped show me that the water was leaking into the bowl. I wrongly assumed that since I applied pressure to the flapper to make sure it sealed that it was not the problem. But the flapper was the problem. Upon taking it out and inspecting it the whole thing was disintegrating and there were cracks allowing water through it.

Answer 1

Turn off water to closet. Empty bowl. Thoroughly inspect flapper for nicks; its attachment to the hubs that hold it; and it’s ove,tall condition; then wipe clean the flapper and the housing on which it rests. Check the water fill tube which fits into the upper end of the vertical pipe. Is it damaged? Is it snug? Is it positioned to drain into the vertical tube? Turn water back on - fill water closet. Flush. Fixed?

Answer 2

Even though you mentioned pressure on the flapper not helping, you might still want to shut off water valve and remove the flapper and inspect. I've noticed the last few times I've had a similar problem that the flappers I've been getting from local big box has a rubber gasket that is two rings sandwiched together during manufacture. Now the weird thing is that water will start somehow getting sucked/injected/transpiring in to little pockets between the two rings forming little water filled "blisters". It usually takes many months, maybe a couple of years. Once this happens I cannot squeeze the water back out without first putting a small slice or puncture in the blister. After that they'll work fine, for a while.

Answer 3

Sounds like water going down the fill tube to me. Could be a crack in the fill tube near the base of it, or like others said the 'flapper' may have a nick/crack/bump in it preventing perfect seal. The sound to me is water in a hollow chamber though, making me think it's that fill tube.

Answer 4

That is the sound of water trickling down the overflow tube. From the looks of it, the tank level is all the way to the top of the tube, it may be going over the top, or it may be the "refill tube", the little flexible pipe that goes into the overflow tube. That pipe sends water down to the rim after the big flush to refill the bowl while the tank refills. In either case, these are the SYMPTOMS of the fact that your fill valve is not completely closing. It's likely just worn out and needs to be replaced. It's not difficult, you can see plenty of videos on Youtube on how to do it if you want to do it yourself.