How to do a wax seal

Plumbers are expensive, one of the most expensive professionals you can hire to work in your home. While some projects require professionals skill,  replacing a toilet or repairing a leaky toilet seal isn’t one of those.

If your toilet is cracked, leaking or you’re changing the look of your bathroom, a big part of that process will be seating the toilet with a new wax seal to create a waterproof connection between the toilet and the household drain.

A toilet mounts on top of a flange that is connected to either a three or four-inch drain. The good news is that flanges vary in thickness at the base to accommodate the two different-sized drain lines, but they are all the same interface between the toilet and the flange on the top.

The wax seal is the key to getting these two together.

A wax seal with rubber gasket attached – Photo by

Aside from very old buildings that may have cast iron drains, most homes now use PVC as drain and flange material. Porcelain remains the predominant toilet material.

The wax seal compresses to create a tight gasket between the toilet and the drain.

There are a few steps to follow in this project that must be done in order.

First, shut off the water supply to the toilet tank.

Shut off valve behind a toilet – Photo by Randy Tucker

Then flush the tank to remove excess water.

Take a small bucket and place it under the water supply connector entering the tank.

Most water connections are only hand-tightened but a set of channel lock pliers will loosen the connector if it’s tight.

The water connection to a toilet connecting the tank – Photo by Randy Tucker

As you loosen the connector place the hose in the bucket while placing the bucket under the connection to the tank.

You’ll get a small amount of water and if you spill a little, no big deal, just use a towel to dry the area.

With the water supply separated and the tank empty, it’s time to loosen the nuts on the mounting bracket at the base of the toilet on each side.

Mounting bolts with decorative caps removed on the base of toilet – Photo by Randy Tucker

A small combination wrench does a great job of this. On rare occasions, when the bolts are rusted, you may have to cut them off with a hacksaw.

With the bolts removed, rock the toilet side to side and lift it off the flange.

If you’re replacing the toilet, remove the tank assembly, then carry the two parts out of the bathroom.

For a new toilet don’t assemble the tank and base until the base is mounted.

If you’re just replacing the flange, keep everything together.

Take a putty knife and remove all of the old wax seals. It will be messy, but putting the old wax in newspaper and tossing the entire pile in the trash is an easy way to keep things clean.

Remove the new wax seal, pull off the clear plastic retainer on the top, then place the seal inside the flange.

Its a good idea to replace the mounting bolts when you install a wax seal – Photo by Randy Tucker

If the bolts are damaged or rusted, take a couple of new brass bolts and pivot the narrow channel of the bolt head into the flange. The wax will help hold these bolts in place as you put the toilet over them and onto the flange.

Ease the toilet onto the bolts, and press firmly to force the wax into each area of the flange and toilet base.

Sit on the base and rock a few more times to set the seal.

Toilet flange that seats under the bowl and connects to the main 3 or 4″ plumbing – Photo by Randy Tucker

Put the washers on the bolts, tighten up the nuts and cover the exposed bolts with decorative caps.

Connect the water supply, turn on the water to fill the tank, and test flush.

You are finished.