Water is starting to seep out of the seams of the vinyl in my bathroom floor when stepped on. I also noticed the toilet caulking seems to be separating. I am not sure exactly where the water is coming from, my thoughts was

  1. Water from stepping out of the shower.
  2. Toilet is leaking underneath? (Not sure if that’s a thing)
  3. Tub is leaking underneath (maybe from drain. Note: the tub was refinished because of cracks within the last 2 years).

Is this a serious concern for mold underneath the toilet and flooring? How big of a repair is this? Can I do it myself as someone with basic home project experience?

  • Do you have access to the area below the floor?
    – Mattman944
    Commented Nov 6, 2023 at 8:35
  • Related: diy.stackexchange.com/questions/32836/… Commented Nov 6, 2023 at 8:56
  • 8
    There's no chance you would have water coming up from through a vinyl floor from stepping out of the shower. There's definitely some sort of leak.
    – JimmyJames
    Commented Nov 6, 2023 at 17:26
  • 1
    If it is an old bathroom, someone might have done a lazy renovation and there could be another waterproof layer underneath. That could explain how water could pool below the vinyl. It will still grow all kind of nasty stuff in between, but wouldn't immediately damage structures.
    – jpa
    Commented Nov 6, 2023 at 18:42
  • Definitely concerning. Could you provide some information about the room/building? I.e. is there a level below the bathroom? What is the floor beneath the vinyl made of? How long has this been happening for? Hope you can fix it soon! Commented Nov 8, 2023 at 14:59

5 Answers 5


To directly answer the "question": Unless you live on a slip-n-slide, water coming out of the floor is very, very concerning. Although ... usually water will leak down into the floor, into the ceiling below, and the floor below. There is a small chance that your water somehow is contained inside the bathroom floor, which would be a good thing if you deal with it urgently.

I would rip up the vinyl floor, mop up the water, and observe to see where it's coming from.


I wouldn't worry too much about mold. I'd worry about the level under the bathroom and the subfloor eventually rotting out.

Yes toilet can leak underneath. Yes you can do it. First is to figure out where the water is coming from.

  • 2
    I'm 95% certain it is the toilet's wax seal.
    – user177013
    Commented Nov 6, 2023 at 18:19
  • 1
    I had an issue where I thought it was the toilet but the shower valve was leaking and the surface tension of the shower wall and tub deck held the water against the surface and then it ran down the side of the tub wall to the floor. If you have 2 bathrooms, turn water off for the toilet and drain it and don't use it. Dry out floor completely with fans / dehumidifiers and heat. Then if you are sure replace wax seal. Commented Nov 6, 2023 at 20:10
  • 1
    Yeah, there certainly are exceptions. As for waiting to replace a wax seal, I'd say, they're so easy and cheap to replace, might as well do it and cross it off the list.
    – user177013
    Commented Nov 6, 2023 at 21:17
  • 1
    You can also have a pipe leak in the walls, or badly sealed showers, but toilet is done first because it is the most common, most severe, and done relatively cheap. The last thing you need is ripping out walls and then find that it is the toilet.
    – Nelson
    Commented Nov 7, 2023 at 1:18
  • 1
    @Nelson "The last thing you need is ripping out walls and then find that it is the toilet." Which I have done...
    – user177013
    Commented Nov 7, 2023 at 15:23

Is this a serious concern for mold underneath the toilet and flooring? Mold can live anywhere there is moisture, food, and the correct environmental conditions. You have provided all three. So yes, mold is definitely a real concern.

How big of a repair is this? There is no way to know until you determine the source(s) of the water and the damage the water (and possibly mold) has caused.

Water seeping out of the seams of your flooring is an indication that the property has one or more significant problems. That's not normal.

Can I do it myself as someone with basic home project experience? Probably not, given the basic level of questions that you are asking. Please don't get me wrong, they are good questions. But given the questions you are asking, I think professional help is warranted. Note that if mold is present, special precautions need to be taken as some mold species present a significant hazard to human and animal health.


Something is leaking. It could be a bathroom fitting, it could be something inside the walls, it could be the roof!

Is this a serious concern for mold underneath the toilet and flooring?

It's worse than that, prolonged dampness can destroy many building materials.

How big of a repair is this?

First you need to stop the leak, then you need to dry out and assess the condition of the building.

Can I do it myself as someone with basic home project experience?

Possibly, but I suspect you will need guidance from an expert who can actually inspect the building, if you can't find the leak call a plumber.

However as the floorign will need to be redone regardless removing the vinyl may make it easier to identify the source of the water.


I'm fairly confident it is the toilet's wax seal. This is the portion of the toilet that takes your flushed water and puts it down the drain. The fact that the toilet caulking is cracking indicates that it was perhaps bumped pretty hard, and that broke the wax seal. Check your memory and see if this water from the floor coincides with toilet flushing. A slow leak would slowly find the low spots and drip somewhere else. The idea that the water is squishing out of the vinyl flooring indicates that the relatively large amount of flushed water is missing the drain with each flush. This same thing can happen on a shower or tub drain, but they are so heavy that being bumped (the typical cause) is unlikely.

It's also very easy and cheap to check and redo a toilet seal, making a great place to start looking for a leak. Go to the hard ware store and get a new wax seal. They'll be less than $10. The toilet is held to the floor with only two bolts on either side, and are usually covered with a cap. Simply remove the bolts, turn off and remove the tank water, then take the toilet off the floor and investigate. You are looking for whether the wax seal looks like it was holding up along the toilet-drain connection, and you are also looking for signs of water especially saturated in the area. There are many YouTube videos out there to show you specifics.

Alternatively, you can simply not use the toilet for about a week, and see if the water problem persists. I'm confident enough in your description that it is the toilet's wax seal that I think you can try this waiting strategy to verify, instead of removing the toilet at the start. But since a toilet seal is such an easy DIY project, I say just pull it off and redo it.

As for long term seriousness, if this is a new development, it will probably be fine once you find the leak and stop it. If there is a ceiling below this bathroom floor, it won't be long before you start seeing the water come out of it. You definitely need to address this immediately.

  • The wax seal mainly prevents sewer gases from escaping. The only time it might prevent water from escaping is when the toilet is flushed, and unless you have a severely clogged waste pipe, not much water is going leak. I've had old wax seals that were completely gone, and the observable sign of that was a terrible smell, not water.
    – JimmyJames
    Commented Nov 6, 2023 at 22:34
  • @JimmyJames Opposite experience... Water in my basement ceiling and everything, only when I flushed. I've fixed plenty of bad toilets with water coming out from under it too.
    – user177013
    Commented Nov 6, 2023 at 22:36
  • Was this an old toilet with a multi-gallon flush? Hard to imagine how you could have enough water from flushing that somehow defied gravity, avoiding falling into the large hole below the siphon and went sideways to flood a floor. Also, if that was the case, that would mean the water coming out of the floor would smell, well, bad.
    – JimmyJames
    Commented Nov 6, 2023 at 22:41
  • 3
    I don't want to deny your personal experience and it's interesting, but from my own personal experience in amateur plumbing and a minor in physics, I wonder if your waste pipe or vent was obstructed. I can see a little bit of water (and I saw evidence of that when I replaced a fully gone seal) getting out but enough where its causing real damage is hard to understand.
    – JimmyJames
    Commented Nov 6, 2023 at 22:55
  • 1
    This is certainly a possibility but from the information provided I'm not sure I'd be as confident with jumping to the conclusion without further information. Commented Nov 8, 2023 at 15:18

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