...but have you ruled out a weeping tank? In some very moist bathrooms where there's condensation and a difference in temperature (e.g. very cold water in the crapper tank/warm moist air from the shower in the bathroom) condensation can form on the tank and drip down on the floor behind the toilet.

Could it be that?

If it is, you just throw a dirty towel back there before you have a shower, to catch any drips, and after you towel off yourself with a clean towel, towel off the crapper tank, too--and leave the door wide open after you're done to get rid of the moist air if you do not have a fan.

Guess I'll try the rag/towel around the toilet trick and make sure to use the fan for a while and see what happens, as I keep an eye on the area around the pipe in the crawl.

Another factor is there is no caulk around my toilets - moisture could be getting under there from condensation/shower or even sink and causing this.

. . . . at that time, you probably won't see it at all.

This was a more common problem in houses some decades ago. I recall they used to make "tank cozys" to wrap the tank, insulate it against normal condensation and absorb the heavier after-shower condensation. I haven't seen them in years and years.

Had a guy with one of those moisture meters come in today. It went all beepy around the base of the toilet for an inch or two (but nowhere else including near the shower or in the other bathroom) so I'm guessing it IS a damn leak.

Crap. Literally. Pfft.

There are things that can go wrong that are glossed over or not mentioned.

The water supply valve may be stuck or won't completely close.

The toilet flange may be broken or rusted through. That could be an easy fix or a major problem. It it is old cast iron and cracked, you *will* need a plumber since it needs to be replaced and the joint sealed with oakum and lead. If it is plastic, you may or may not be able to fix it yourself.

The suggest wood might need to be removed. That only hints at what kind of job you might face.

All in all, it is an easy repair . . . . until it isn't. And this is *really* a matter of YMMV.

Guess I'm going to turn it over to a plumber - I have wood floor below the vinyl too but may be able to dry that out IF it's just surface and only a few inches - that will take a few days though, then the whole thing goes back on and I x my fingers no more damn leak. You never know what you're going to find under there.

I'm frankly petrified.

EDIT: It is a 'newer' home, built 2001 so hopefully no old lead flanges.

They probably used 1/4 turn ball valves for the supply shut-off. They're pretty reliable. Then with it only being 12 years old, even the crappiest flange ought to still be in perfect condition.

Good luck.

I had a plumber remove the toilet, seal AND flange. He didn't want to remove the flange but I made him so I could see the floor and subfloor and peel back the vinyl. Sure enough, floor around the back had been wet and one spot was particularly bad - the thing was leaking under there and the flange was cracked in one place. It was a few millimeters from seeping thru subfloor in one spot.

So. $$$$$$$ for the plumber and for a flooring co. to cut out the icky wood and replace it with new, along with replacing the vinyl and plumber will place a coupling/flange/new wax seal and replace the toilet.

Damn good thing I caught it when I did or the mess would have been under a wall soon. Even though it's costing me money I didn't intend to spend, I think it was a good call to have the whole thing taken out NOW so I could see wth was going on before it got worse.

Gray or black stuff around base of toilet under vinyl installed over wood floor/subfloor is not something to mess with.

So toilet sits in my tub for now awaiting flooring repair/replacement and then toilet re-install.

That pipe is untrapped and open directly to the sanitary sewer. Sewer gas is a decidedly unwelcome guest in your house.

You can stuff a rang in the hole or you can even bridge over it with something like blue painter's tape. Yu could even bridge it with saran wrap and then just tape the edges to the floor.

You just wanna hold the smell back.

To remove the flange. There is a hole tho - I have a rag lying over top of it - bathroom door closed. Crawl is closed up but have had door open - might get stinky in there before they get it all back together in a few days.

Edit: I did go ahead and stuff that rag into the hole in the floor of the bathroom and put a garbage bag over it and taped it down so hopefully that will abate any smells.

He should have.

He sawed off the flange and left it until re-install.

Best wishes for a smooth repair!

I'd check for a slow leak around the water line, or a leak around the bolts connecting the tank to the bowl.