Simple Steps to Identify and Repair a Toilet Seal Leak

Simple Steps to Identify and Repair a Toilet Seal Leak

You might have seen water under or around your toilet.  There’s a good chance that’s because you have a toilet seal leak.

Fix Toilet Seal LeakA toilet seal is a wax gasket, similar to a donut, that fits where your toilet and floor meet.  It’s supposed to keep moisture from leaking out of the toilet and damaging your floor and sub-floor.

Toilet seal leaks are a common problem.  They’re common enough that people wonder whether the seals were installed properly.  And that’s understandable.  When you discover damaged flooring after a toilet seal repair, you’ll naturally question a contractor’s work.

Replacing a toilet seal can be a big job for an inexperienced do-it-yourselfer.  If you decide to tackle this job yourself, do it on a warm day.  At least 70-degrees Fahrenheit will ensure the wax is soft enough to mold easily.

Repairing a toilet seal leak involves two major steps: removing the old toilet seal and then installing the new seal.  Each of those involves a series of smaller, simple steps.  So get your toolbox and grab the new seal and a pair of rubber gloves.

But before you jump in, remember…  The leak could be a problem with the toilet, not the seal.  So if your plumbing drain is working, and the last repairperson was qualified, it’s best to bring in a professional.  You might need to replace the toilet to avoid further floor damage and interruptions.

Step 1: Remove the Old Toilet Seal

(Remember, first you’ll remove the old seal and then install the new one.)

Turn off the water supply.  Before you remove anything, turn off the toilet’s water supply.  You can typically find the knob to turn off the water supply on the wall next to the toilet with a water hose leading to the toilet.

Empty the tank and bowl.  Then empty the tank and bowl of water by flushing repeatedly.  Be sure there isn’t any water left in either one.  Use a rag or sponge to clear any excess water.

Disconnect the toilet from the floor.  Do this by removing the nuts from the bolts that stick up from the floor through the base of the toilet.  There might be plastic caps covering each one that need to be removed first—they should pop off easily.

Disconnect the toilet from the water supply line.  You can probably do this by hand.  Find the plastic, ridged screw that secures the water line to the toilet and turn it counter-clockwise to loosen it.  This is the same water line you turned off a few steps back.

Loosen and remove the toilet.  Place all the pieces you’ve removed a safe distance from the toilet.  Now position yourself over the toilet and rock the bowl—not the tank—from side-to-side.  This will loosen the seal (and caulking, if there is any, where the toilet and floor meet).

After it’s loose, you can completely remove the toilet and place it to the side.  Clean both the toilet and floor completely.

Step 2: Attach the New Toilet Seal

Put the new wax seal in place.  Center the seal over the flange in the floor.  The flange is shaped like a disk, or collar, and is used to attach the toilet to the floor.  Be sure the rounded side of the seal faces up.

(You’re almost finished.  You’re basically going to re-connect everything you disconnected earlier.)

Fix the seal in place.  Now put the toilet back in place over the new seal and bolts.  Next, apply weight to the toilet to fix the seal in place.  The easiest way to do this is to apply downward pressure by sitting on the toilet.

Secure the toilet to the floor.  When you’re sure the bowl is level with the floor, reattach the nuts you unscrewed to the bolts that stick up through the toilet’s base.  This will re-secure the toilet to the floor.

Reconnect the water line.  Reconnect the water line to the toilet and tighten the plastic, ridged screw that holds it in place.

Turn the water supply on.  Now you can turn the water supply back on using the same knob as earlier, next to the wall (at the opposite end of the water supply line from the toilet).

(If you want to be extra sure your toilet base is sealed, apply caulk to seal the gap at the base of the toilet, where it meets the floor.)

Check for leaks.  Now flush the toilet and watch for leaks around the base.  If you don’t see any…

Congratulations!  You’ve just repaired your toilet seal leak.  If you used high-quality materials you’ll enjoy a leak-free toilet.

If you want guaranteed help identifying and fixing your toilet seal leak fast, visit or call McDonald Plumbing, Heating & Air for help today.

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