(636) 299-3854

DA2Is there a small pool of water collecting where your toilet meets the floor? Or does that floor around the toilet feel spongy and/or lifting up? If so, you might have a bad seal under the toilet. The seal, on the bottom of a toilet, where it rests on the floor, is a gasket made of a ring of wax that can help prevent damage to flooring and sub-flooring. Small leaks that are trapped beneath the toilet will eventually rot floor surfaces and framing, so the repair should be done right away. The longer you wait to repair a seal leak, the more expensive it will be to fix. If you have to replace the finished flooring or the underlayments, subfloor or framing, your cost will skyrocket.

The good news is if you catch a seal quickly it won’t be that difficult to fix. Arch Plumbing always recommends having a professional plumber repair any plumbing issues. Below is a description of how to replace the seal under a toilet.

Be sure to do this repair when the temp is a minimum of 70 degrees Fahrenheit. This helps to keep the wax pliable. If the leaky seal is under an existing toilet, make sure to wear rubber gloves. If the installation is for a brand new toilet in new construction, skip to Part 2.


– Shut off the water supply. You can do this at the toilet but there’s chance you will need to go into the garage or basement to shut off the water.

– Next, flush the toilet a few times to empty the tank and toilet bowl.

– Use a sponge to soak up and take out any left over water in the tank and toilet bowl.

– Take off the nuts. Penetrating oil and pliers may be needed to remove them.

– Disconnect the water supply line.

– Now you can rock the toilet back and forth gently to break the seal and caulk. Make sure you grip the bowl and not the tank so you don’t break or crack the tank where it is bolted to the bowl.

– Take off any remaining parts of the old seal from both mating surfaces. You are now ready to go to Part 2.


– Place the new wax seal over the flange on the floor with the round side up. It must be placed exactly centered over the opening. You want to make sure both the bolts are in place.

– Now lift the toilet up and place it over the flange and seal, making sure to keep the toilet as level as you can.

– You can sit on the toilet to reinforce the new seal.

– Make sure the bowl is level.

– It is now time to replace the nuts that you removed earlier. Tighten them by hand. This will alleviate cracking the base of the toilet bowl.

– Reconnect the water line.

– Turn the water supply back on and let the tank refill. If you want the tank to refill slowly and with lower pressure, only turn the water supply back on half way.

– Flush and check for any leaks coming from the toilet.

– Now use silicone caulk to create a seal where the bowl meets the floor.

Arch Plumbing has been in the service business since 2008 providing quality plumbing services