Where is my Toilet Water going?

My Toilet tank is leaking, as evident by the water tank level going down, and the tank then refilling constantly. I have ruled out leaks from the bolts and from the water inlet valve and hose. I have noticed that the water only goes as low as the rubber flush valve in the tank. So my guess is that is where the leak is.. But if this is correct, how come no more water continues to go into the bowl of the toilet? (in other words, would the bowl keep filling up till it overflows?) My understanding is that the tank water goes into the bowl via the flush valve... Thus, if this is where the leak is, wouldn't the bowl overflow? Or, if not, where and how is the water going? I want to make sure I am repairing the right thing before I replace anything! Thanks!!!

ATVguy54, I actually had a similar problem where the water level of the toilet bowl remained unchanged but the water kept running. It was not going in to the bowl and I determined that there was something wrong with my flush valve assembly.

At first I was going to replace the whole thing with a Fluidmaster one but I decided to follow an online video of how to do maintenance on the assembly. So I took it apart (didn't even need to detach anything from under the tank) and cleaned it out. Turns out some chunks of sediment had gummed up the works. Once I cleaned it and put everything back together it was working fine.

Can you provide a picture of what your fill valve looks like?

Sounds like you have a bad flapper or a bad flush valve gasket. 99 percent of the time it's a bad flapper. Water is slowly leaving the tank into the bowl via bad flapper or flush valve gasket and simply draining through the toilet drain. The reason you do not hear a flush because the water is slowly going into the bowl. We (Plumbers) call it a phantom flush - You hear the toilet refilling but do not hear it flush. I would replace the flapper first.

I just had this problem last week in my master bath, at night I could here it tinkling down the drain, my filler is one where you have to push the handle before it would fill so when I went to use it there would be no water in the tank. Replaced the flapper and all is good now.

Yeah, sometimes the flappers get distorted and don't seal properly anymore. Before just replacing it you should examine it to see if it looks wavy and also try adjusting how it sits to see if it stops the toilet from running. Sometimes cleaning it (without damaging it) and the surface on which it sits can help lit get a better seal. If it turns out to not be the flapper then you might need to clean or replace your flush valve assembly (which is really not that hard to do).

I replaced the flapper in my toilet but it still did not stop the constant running so I had to take apart the flush valve assembly.

As said above, start small with a flapper replacement. It's important to match the type of toilet with the type of flapper, also. Most big box stores carry all of the major labels so look for a manufacturer name printed on the bowl where the seat mounts or inside the tank/inside the tank lid. Universal kits aren't always a perfect match, but with the right info the rep at the store should be able to help you.With a new flapper properly seated, you should stop the leak.
If you still have leaking, the flush valve could be leaking through. That would involve a bit more work, as the other guys have pointed out. Take a few pics, if you can. They always help.

Definitely the flapper. Replace it and it should be good to go.