Mystery Toilet Leak

[Fractal20]

Hello all, I recently purchased my first home and I'm rapidly discovering the joys of plumbing. Prior to these first projects, I did not have any experience with plumbing. To get to my problem, while in the crawlspace I noticed damp wood all around the toilet. I assumed it was the wax seal. I replaced it and it still was wet in the crawlspace so I replaced it again. It still didn't fix the problem, so I just replaced it a 3rd time and used the "Perfect Seal" product that combines a rubber gasket with a wax seal and seems fairly idiot proof. Yet again the sub floor is getting wet.

I would assume that the seal is still the issue, but there are a few things I have recently realized that make me think the seal is not the issue or at least not the only issue. To summarize:

1) The toilet has not been used in days and I have been drying the sub floor with a space heater in the crawlspace, and it will dry out significantly. Then when I turn off the space heater and check back in a few hours, the dampness has returned, all while the toilet has not been used. My understanding is an issue with the wax seal should only be evident if the toilet is being flushed.

2) I did not re-caulk around the base of the toilet, and there are two shims under the backside of the toilet and there is no apparent pooling of water on top of the floor. It's only evident from the crawlspace. I figure that I should see pooling of water around the base of the toilet if the wax seal has issues and the base of the toilet isn't caulked. Though again, I haven't been flushing the toilet in recent days in order to try and figure out where the water is coming from.

Based on the observations in (1) and (2), does it seem correct that there must be an issue besides the seal? If so, what could it be? I've carefully checked that the tank isn't leaking, and I even added some silicone around the bolts in the tank. To the best I can tell, there is no leaking from the tank, and again, there is no visible pooling on the floor. I also can't see any issues with the water line to the toilet. It is a copper pipe to a compression fitting style shut off valve and then the braided line to the toilet. I can't fine any leaks along that, though the compression nut firmly presses the cap onto the floor, so I can't look under that.

Any suggestions? If it is helpful, I have attached a picture of the damp sub floor from the crawlspace and a picture of the shut off valve to try and show the cap portion that I haven't been able to look under.

 

[johnjh2o]

It could be the tank to bowl nuts and washers or the gasket on the flush valve.

 

[havasu]

Lay little pieces of toilet paper on the floor around the entire back of the toilet. This will give you an instant indication where the leak is originating from and where to start looking, just from the discoloration (wetness) of the toilet paper.

 

[Fractal20]

It could be the tank to bowl nuts and washers or the gasket on the flush valve.

The flush valve, as in the circular gasket that is lifted up when you flush the toilet? I'm not sure exactly what you mean. Specifically, do you mean that water would be leaking into the toilet bowl, which then is going over the p-trap and leaking through the wax seal? Or that water is leaking through gasket between the tank and lower half of the toilet and then running down the outside of the toilet?

To both responses thus far, I will try to lay toilet paper around the toilet everywhere. I haven't done that, but I have been feeling around for wetness with my hand...

 

[Jeff Handy]

Put some food coloring in the water in the tank.
If the water in the bowl starts getting colored, you know you have a leak from tank to bowl.

If you see colored water on the floor, you know you probably have a leak from the tank to bowl connections.

There can also be a crack in the china anywhere, even inside the toilet trap way, where you will never see it.

Looks like mineral build up on the floor tile, water might just be leaking from somewhere and running behind the wall and down to the crawl space.

It could be a leak from a shower curtain or shower door, or the shower drain or bad caulking.
The shower valve might be leaking behind the wall.

Your toilet fill valve might be going bad, and constantly filling a little bit, which sends water down the overflow tube.

The flapper on the flush valve might also be leaking a little, which might equal the excess water coming from the fill valve.

You can post some pics of the inside of the tank, when the tank is full and sounds like water has stopped running.

If you turn off the toilet shutoff valve, the wood should dry out.

If it stays wet, then the water is coming from somewhere else.

Like a bathroom above there.
Or a nearby water pipe, a leaking hose faucet, roof leak, bathroom behind that bathroom, ground water leaking in from poor grading, many possibilities.

 

[johnjh2o]

The flush valve, as in the circular gasket that is lifted up when you flush the toilet? I'm not sure exactly what you mean. Specifically, do you mean that water would be leaking into the toilet bowl, which then is going over the p-trap and leaking through the wax seal? Or that water is leaking through gasket between the tank and lower half of the toilet and then running down the outside of the toilet?

To both responses thus far, I will try to lay toilet paper around the toilet everywhere. I haven't done that, but I have been feeling around for wetness with my hand...

No, the gasket is the one used to seal the flush valve to the tank.

 

[Fractal20]

Put some food coloring in the water in the tank.
If the water in the bowl starts getting colored, you know you have a leak from tank to bowl.

If you see colored water on the floor, you know you probably have a leak from the tank to bowl connections.

There can also be a crack in the china anywhere, even inside the toilet trap way, where you will never see it.

Looks like mineral build up on the floor tile, water might just be leaking from somewhere and running behind the wall and down to the crawl space.

It could be a leak from a shower curtain or shower door, or the shower drain or bad caulking.
The shower valve might be leaking behind the wall.

Your toilet fill valve might be going bad, and constantly filling a little bit, which sends water down the overflow tube.

The flapper on the flush valve might also be leaking a little, which might equal the excess water coming from the fill valve.

You can post some pics of the inside of the tank, when the tank is full and sounds like water has stopped running.

If you turn off the toilet shutoff valve, the wood should dry out.

If it stays wet, then the water is coming from somewhere else.

Like a bathroom above there.
Or a nearby water pipe, a leaking hose faucet, roof leak, bathroom behind that bathroom, ground water leaking in from poor grading, many possibilities.

I was able to put food coloring in the tank today. It took a few hours, but there ended up being a faint trace of it in the toilet bowl. So it seems like some water must come through. So I imagine it the flush valve must leak. The only thing is I have never heard the water running in terms of the tank refilling from losing enough water...

Do you think the most likely thing is that the toilet seal is still bad and so water is slowly leaking into the bowl, which then leaks over the p-trap and out the toilet seal? I'm still surprised that there isn't any pooling around the base of the toilet.