What it usually looks like
- A puddle or damp ring around the base of the toilet after flushing
- The toilet rocks or shifts slightly when you sit on it
- Discolored, soft or lifting flooring around the toilet
- A sewer smell near the toilet that gets worse after a flush
- The caulk around the base is stained or has water seeping from under it
- A ceiling stain in the room directly below the bathroom
Likely causes, most common first
The wax ring has failed
The wax ring compresses between the toilet horn and the flange to make a seal. Years of tiny movement, a toilet that was set with a ring that was too thin, or a flange that sits too low all leave a gap. Once the seal is broken, every flush pushes some water out under the bowl. A failed ring is the most common cause and the cheapest to fix, provided the floor under it is still sound.
A loose or rocking toilet
Closet bolts loosen, nuts corrode, or the floor is uneven and the toilet rocks on the high spot. Movement breaks the wax seal every time it happens. Shimming and tightening is only half the fix; the ring has to be replaced too.
A broken, corroded or low flange
The flange anchors the bolts and holds the ring. Cast iron flanges rust until the bolt slots break off; plastic flanges crack when bolts are overtightened. A flange that sits below the finished floor after new tile or vinyl was laid cannot compress the ring enough to seal. All of these need a flange repair ring or a new flange.
Condensation on the tank or bowl
In a humid bathroom in winter, a cold tank sweats and the drips run down the outside of the bowl and collect at the base. It looks like a leak but there is no sewer smell and it happens without flushing. An insulated tank or a mixing valve on the supply addresses it.
A leaking supply line or tank-to-bowl gasket
Water dripping from the supply connection or from the bolts and gasket between tank and bowl runs down and pools at the base. Dry everything and watch where the water first appears before blaming the wax ring.
A cracked bowl
Rare, but a hairline crack in the porcelain near the base lets water weep out continuously, with or without a flush. A cracked bowl means a new toilet.
Safe things to check yourself first
- Dry the floor completely, then flush and watch exactly where water first appears
- Try rocking the toilet gently with both hands on the bowl; any movement means the bolts or the flange are the issue
- Check the supply line connection and the tank bolts for drips with a dry paper towel
- Look at the caulk around the base; if it is intact all the way around, water underneath may be trapped and worse than it looks
- Note whether the water is clear with no smell, which points to condensation or supply, or has an odor, which points to the seal
- Stop using the toilet if the floor is soft until it is fixed
Stop and call if
- The floor around the toilet is soft, spongy or sagging
- There is a stain or drip on the ceiling below the bathroom
- The toilet rocks and water appears with every flush
- The flange is visibly broken, rusted or sits well below the floor surface
- A sewer smell persists even after the floor is dry
How we diagnose and fix it
- Pull the toilet and inspect the flange, the subfloor and the closet bend before deciding what the repair actually requires
- Replace a failed flange or install a repair ring, and raise a low flange with spacers so the ring seals properly
- Set the toilet on a new wax ring or a waxless seal with new brass bolts, shim it level, and caulk the base with a gap left at the back so a future leak shows
- Replace a cracked bowl or an old toilet with a new model if that is the better value, with your approval first
- Point out subfloor damage and document it with photos for your insurance or contractor; we do not do restoration but we will tell you what we found
Around Kitsap, Pierce and Mason counties
Older homes in Bremerton, Port Orchard and Manchester often have cast iron flanges from the 1950s and 60s that have rusted to the point where the bolt slots are gone, and a new wax ring alone will not hold. We also see a lot of toilets set on top of a second or third layer of vinyl flooring, which leaves the flange too low to seal. In our damp winters, a bathroom without good ventilation also produces enough tank condensation to fool people into thinking the base is leaking.
Questions people ask
Can I just tighten the bolts to stop the leak?
Tightening stops the rocking but does not reseal a wax ring that has already been broken. Overtightening also cracks the porcelain. The ring has to be replaced.
How long does a wax ring last?
Indefinitely if the toilet never moves. Most fail because of rocking, a low flange, or a toilet that was reset without a new ring.
Should the base of a toilet be caulked?
Yes, around the front and sides, with a small gap left at the back so a leak can show itself instead of being trapped under the bowl where it rots the floor.
The leak is only sometimes. Why?
A marginal seal can hold against a normal flush and fail when the toilet is sat on heavily or when the drain is sluggish and water backs up briefly in the horn. It will not get better.
How much damage can this cause?
A lot, quietly. Water under the toilet soaks the subfloor and the joists below, and on a second floor it ends up in the ceiling. We have replaced floors that failed from a toilet that only leaked a little for a few years.