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Short Summary
Main recommendation: when a toilet leaks underneath after a clog, the likely culprit is a stoppage in the drain below the bowl that pushes water past the wax seal, and the fix is to remove the toilet, replace the rotted closet flange, and reseal it with a flexible gasket. The video demonstrates this on a home whose cast-iron flange had rotted away after a tile remodel had raised the floor and left the old flange well below the new surface.
Key Points
- A siphon jet toilet uses a short leg and a long leg in its trapway; once water rises over the hill of the short leg, it pulls waste down the long leg.
- A clog deep in the drain pushes pressure back through the wax seal, while a clog in the trapway would simply back water up inside the bowl.
- The toilet's brass bolts had rusted in place, so the host cut them off with a mini hacksaw rather than trying to remove them.
- A remodel had built the tile floor up around the toilet, leaving the cast-iron flange far below its proper height and supported by non-watertight spacers.
- After a standard cast-iron flange and a screw-tightened gasket flange both failed to fit the oversized old pipe, an expanding internal gasket flange with Allen screws was used, along with a reusable flexible gasket in place of a wax seal.
Details Worth Noting
- Concrete instructions:
- Turn the shut-off valve clockwise to stop the water supply.
- Flush the tank so most water drains into the bowl, then move the float out of the way and sponge out the remaining tank water, leaving only enough that it won't spill when the toilet is moved.
- Disconnect the two floor bolts and the water supply connection, cutting seized brass bolts if they won't turn; catch residual water in the pipe with a rag.
- Pry off the old wax seal and inspect the flange; if the cast-iron flange is rotted, break away the remnants and clean the outside of the pipe.
- Choose a closet flange that fits the pipe's dimensions; a heavy, oversized 1880s cast-iron pipe may not accept modern flanges, so use an adjustable device with a gasket and Allen screws that expands to seal the inside of the pipe.
- Set spacers to hold the flange at the correct height relative to the floor and confirm the keyway is positioned for the closet bolts.
- Tighten the flange so it is solidly in place, then install the closet bolts into the keyways.
- Use a flexible gasket on the underside of the toilet instead of a wax seal, since wax softens in summer and gets brittle in winter; a flexible gasket can also be reused and repositioned.
- Place the plastic washer first, then the stainless washer and brass nut on each bolt, and tighten.
- Trim any closet bolt that is too long for the cap to fit, using the mini hacksaw.
- Turn the water back on and fill the tank, then check for leaks.
- The host notes the wax-seal problem and the flexible gasket as a practical alternative, and warns that the floor-level mismatch likely caused the leak.
- The exact flange model and gasket brand are not named in the transcript.
Bottom Line
A leak under a toilet after a clog should prompt a check of the drain and flange beneath the floor, not just the bowl, because a rotted flange or non-watertight spacers can let pressure escape through the seal.
