Toilet Leaking from Base: Causes and How to Fix It

Water on the floor around the base of your toilet is one of those things that needs fixing, ASAP. Not only is it a pain, but it can cause water damage, mould, and all sorts of other costly issues if you don’t address it straight away. Whether it’s a slow leak or a steady stream, a toilet leaking from base is something you need to get a handle on before you can start to fix it.
Fortunately, you don’t need to be a qualified plumber to know what to look for and figure out what’s going on. In this article, I’ll cover the most common causes of a toilet leaking from the base, what you can safely check for yourself, and when to call in a professional. By the time you’ve finished reading, you’ll know exactly what to do and be empowered to take action.

Why Is Your Toilet Leaking from the Base?

If there’s water on the floor around the base of your toilet, it means something has moved or deteriorated somewhere in the system. The base of your toilet is where the bowl meets the floor. It’s fitted with a wax ring (or possibly a rubber gasket) that ensures water doesn’t seep out between the porcelain and the floorboards. If the wax ring fails, water from the bowl will escape and form a puddle.
From my experience, it’s crucial to work out where the leak is coming from to start with. Is the water coming from the bottom of the bowl, or is it running down from somewhere higher up? It matters, because it rules some things in and out. In most cases, a toilet leaking from base will be caused by one of a few common issues, which is a good thing, because that means they’re relatively simple to fix.

Common Causes Behind a Leaking Toilet Base

A wax ring is a ring of compressed wax that sits between the outlet of your toilet bowl and the flange of your drainpipe. It does a great job of keeping everything sealed up, but it’s not indestructible. Over time, your wax ring can become compressed or cracked, simply because of exposure to water, changes in temperature, or your home settling.
If the leak is coming from the bowl or tank of your toilet, it could be because the porcelain is cracked or broken. This might be because something heavy has been dropped on it, or because the toilet isn’t sitting level on the floor. You might find the leak seems to worsen when the tank is refilling (if the crack is in the tank). If the tank is cracked, you might find water is pooling at the back or side of the toilet, rather than the base.
Sometimes your toilet not flushing properly might be related to your leak, especially if we’re talking about a problem with the pressure of the water coming into the toilet, or a mechanical fault inside the toilet. Loose tank-to-bowl bolts, bad toilet fill valve, broken cistern inlet valve or faulty flush valve could be causing the leak and flushing issues and this is where you need to decide how to fix toilet flush. A broken or misaligned flange (the fitting that the wax ring mounts to and is set into your floor) will cause an uneven mounting surface for the wax ring, leading to a toilet leaking from base.

Step-by-Step Guide to Diagnosing the Leak

To determine where the leak is coming from, you first need to shut off the water supply to the toilet. The shut-off valve is located behind or to the side of the toilet. Now you’ll be able to inspect the leak without having to fight the water continuing to flow into the tank and bowl.
Dry the area around the base with towels. If you have water pooling around the base, soak up as much as you can with towels or use a wet vac. Turn the water back on and allow the tank to fill while you watch to see when the leak occurs. Is new water leaking from the base as the tank is filling, or does the toilet water keep running? Or is the leak only happening when you flush the toilet? This will tell you if it’s a tank leak or a bowl leak, which is a key first step in understanding how to fix a toilet. 
If you’re still unable to tell where the leak is coming from, place a few drops of food colouring into the bowl water (not the tank water). Wait to see if the coloured water is leaking onto the floor. If the water on the floor is now coloured, you know the leak is coming from the bowl. If the leak persists but the water is not coloured, the leak is originating from the tank. I’ve found this to be a much more effective method than guessing, which could cause you to make repairs to the wrong portion of the toilet.

How to Fix a Toilet Leaking from the Base

If it’s determined that your wax ring is leaking, the solution will be to replace the wax ring. This will require you to remove the entire toilet. Don’t panic, it’s easier than you think! Shut off the water supply and flush the toilet to empty the tank. Disconnect the water line from the toilet and unscrew the tank bolts from the floor. You will need assistance to lift the toilet from the floor and set it on its side on a towel or cardboard.
The old wax ring will now be visible and can be completely removed. Scrape all the old wax from the flange until the flange is clean of all the debris. Place a new wax ring onto the flange and lower the toilet back onto the floor, applying enough downward pressure to compress the wax ring and form a good seal. Reattach the water line and tank bolts, then test for leaks by filling the tank and flushing the toilet a couple of times.
If you have a cracked bowl, you will need to replace the toilet. It’s not possible to safely fix a cracked toilet bowl, and attempting to seal it could result in further damage. If the crack is small and the leak is minor, you might temporarily be able to slow the leak with a two-part epoxy designed for porcelain, but that’s not a permanent solution. If you have a broken fill valve or a bad toilet intake valve, these can be replaced without taking the toilet out, which is much easier. Should your toilet not flushing properly accompany these symptoms, replacing the valve can fix both issues simultaneously.

When to Call a Professional Plumber

If you have a leaky toilet and have ascertained the wax ring is not the problem, it may be time to call a professional. If you’ve discovered the problem is a bad flange or misaligned flange (which you can see by pulling the toilet off and looking at the fitting where the flange is mounted to the floor) you’re now into a problem that involves the plumbing in your house rather than the toilet itself. A professional can tell whether the flange needs adjusting, to be repaired or replaced.
If you’ve ruled out the wax ring and the bowl does not appear to be cracked, and you still have a leak, you may have a trickier issue on your hands, such as the tank seals or the way the toilet is sitting on the floor. A tradesperson will have the tools and the experience to diagnose these more subtle issues. Don’t be afraid to call for help if you’re not sure; the cost of a professional to diagnose the issue is much less than the cost of water damage to your subfloor or the cost of a new toilet because you’ve ruined the one you had trying to pull it.