We've discovered that our toilet is leaking at the base (related question: How can I repair a toilet that is leaking at the base?) and needs repair. However, whoever installed the toilet originally decided to concrete it down to the floor, so a DIY repair isn't that simple.

We've decided to use it as an excuse to get the whole bathroom refitted. But obviously this'll take time (several months). We need to use the toilet in the mean time, so how bad an idea is it to caulk around the base to stop the dirty water dribbling out onto the floor until we can get the whole thing replaced?

It's on the ground floor, if that makes any difference.

  • You are in the UK, most UK toilets have a rearward waste connection not downward. Is your toilet different? If not, are you certain where the leak is from? Toilets are sometimes glued down as well as being screwed to the floor. I'm not clear what you mean by "concreted down". Mar 20, 2016 at 12:45
  • @RedGrittyBrick yes, it does appear to be rearward connection. The leak is likely from that base though, as I can see it bubbling through the sealant at the base when I flush, and there are no drips rolling down the toilet from anywhere else. We had a plumber in last year who couldn't remove the toilet, saying it has been fixed in with concrete. Hmm. It seems it's not as simple an issue as I first thought.
    – JonW
    Mar 20, 2016 at 14:18

3 Answers 3


It is a very bad idea to caulk around the base of a toilet.

It is an even worse idea to caulk around the base of a toilet with a known seal leak.

Do not wait, pull the toilet up and replace the seal and make whatever necessary repairs as soon as possible. You don't know where that nasty waste water will end up if you seal it in.

  • 2
    Caulking seems like an excellent way to forget about the problem until the toilet rots it's way through the floor underneath. Mar 20, 2016 at 19:44

Of course, I'd say remove the toilet & pop down a new wax or foam rubber seal (I prefer the latter). My first toilet went amazingly better than I thought & I even scraped the pipe back to full diameter. I gave it a shot with nothing but pliers & a wax ring's box, contents & back panel instructions (they come inside the box now).

However, as long as "ground floor" means concrete slab & no wood or building structure, then it's fine for a few months. I'd still say replace the wax ring, since you don't know the future & a few months may turn out to be when the toilet finally clogs. To then, find that what the toilet is/was attached to has completely rusted away & a 10-pound/euro job turned into a 1000-pound/euro job.

  • 3
    I disagree that it is "fine" for any length of time. At best there will be untold nasty muck, mold, and bacteria under the toilet. At worst that sewage will find somewhere to drain to other than the waste pipe, like under surrounding flooring or down between the pipe and the slab. Mar 20, 2016 at 13:28
  • 1
    The trap for a toilet is built into the toilet itself. If the joint between the toilet and waste pipe is leaking water, it's also leaking sewer gas. Ignoring the leak is not a good idea.
    – Tester101
    Mar 20, 2016 at 13:47
  • You're absolutely right & I fully agree with your disagreement. That's why I pushed to do it right. But, this is real world stuff & like most people they're fine with it running in & on the floor, wrapping a towel around the base or just wiping it up after they step in it. It's the toilet's fault for leaking clear water & not sludge.
    – Iggy
    Mar 20, 2016 at 13:48
  • @Tester101 Not at all true. Sewer gas is not going to bypass a big fat wide open pipe to find a literal pin-hole.
    – Iggy
    Mar 20, 2016 at 13:49
  • @Iggy That all depends on the pressure in the pipe, and the pressure on the other side of the "pin-hole".
    – Tester101
    Mar 20, 2016 at 13:51

how bad an idea is it to caulk around the base to stop the dirty water dribbling out onto the floor

If your toilet connects like this (as is common in the UK)

enter image description here

Caulking around the base (where it meets the floor) will have no effect.

In the UK, you can also almost certainly disregard advice about wax rings which are used in the US where plumbing arrangements differ.

In general if you have a leak, you need to find the source and replace the seal. In your case this might be the push-fit plastic flexible connector (7) between ceramic toilet (5,6) and plastic soil-pipe (8) below.

enter image description here

These seals cost around £6.

enter image description here

Obviously the issue is removing the close-coupled cistern and toilet. This is usually achievable on a DIY basis. Obviously there is something different about yours since your plumber mentioned concrete preventing them fixing the leak.

I suggest you edit the question above to insert photos showing 1) whole toilet 2) connection to soil pipe 3) how the toilet is attached to floor. That way people can offer better advice.

If your toilet is leaking somewhere underneath, you might be able to use caulk to temporarily contain a small pool of raw sewage within the outer perimeter of the toilet base but it isn't something I would be happy about, particularly if the floor is OSB or similar. Especially if this is upstairs.

  • It is this sort of fitting, I believe, yes. Although I am reasonably sure there is no leak there, as the water is coming from through the sealant at the front of the toilet base, and not running around from the back (as far as I can tell anyway). It may well be that there is a crack inside the pan itself. I will need to investigate further (it is slightly inaccessible back there, so hopefully you are correct in your hypothesis). I shall leave the question as-is though, purely because as it is written it is likely a more common issue for more people than what my situation may turn out to be.
    – JonW
    Mar 21, 2016 at 10:01
  • Even for a UK toilet connection, it's always a bad idea to cover up a leak.
    – stannius
    Mar 22, 2016 at 22:22

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