Underneath toilet

I found a leak in my crawlspace underneath the guest bathroom toilet that may have been leaking for awhile (I don’t go into the crawl space all that often. After some internet searching, I believe it is leaking around the wax ring. I’m confident I could change that, but my real question is about the white stuff I can see from underneath the toilet in the crawl space. Is this a type of mold? Or is it possible just water mineral buildup (we live in the country and have relatively hard water).

If it’s mold, can I just scrub it away with something? The toilet isn’t wobbly and it doesn’t seem like the floor is in poor shape. Thank you in advance.

 

Yes it's mold. (White rot fungi) Sure you can spray it with concrobium or hydrogen peroxide. Borax is another good cleaner with natural surfactants. Scrape it off or lightly sand it while sucking dust with a shop vac. Obviously wear a mask if you are sensitive to mold. But don't imagine you are just going to wipe it off, it grows into the wood fibers and leaves a stain and biomatter behind.

It's likely on both sides of the plywood and under your flooring, but once it dries out mold goes dormant. Unless you are tearing up the floor you can save that for someday down the road.

Maybe paint it with a mold killing primer if it makes you feel good.

An issue as big as the mold is the smell of having sewer water (not just water but urine and feces) soak into the plywood. That smell will be there and perhaps be noticeable until the plywood is replaced.