A toilet gasket, or a wax ring, as it is commonly called, seals a toilet to the plumbing as it passes through the flooring. The seal is important to ensure that water and sewage do not leak past the toilet gasket and out onto the floor. There are many reasons that a toilet gasket might require replacement—floor deterioration, loose toilet bolts and wear over time are a few of the most common.
The plumbing for a toilet typically sits nearly flush with the flooring. A thin metal plate is typically all that secures the plumbing pipe in place—the toilet is also fastened to the floor by that same thin metal plate. Bolts are inserted through the plate pointing upward, and the toilet is positioned over the bolts and lowered into position. The toilet gasket is placed over the sewer pipe prior to the toilet being lowered into position. Once in position, the nuts are threaded onto the mounting bolts and the toilet is secured in place.
It is imperative that the toilet be lowered as straight down as possible to avoid slanting the toilet gasket or squashing it further down on one side than it is on the other, as this could cause a leak. Once the toilet has made contact with the toilet gasket, the toilet is pushed down into the wax ring to achieve a proper seal. The gasket, being made of soft wax, conforms to the toilet's base as well as the flooring and the plumbing and creates a seal.
Over time, flooring can become dry and brittle; this leads to screws that were once tight becoming loose and even pulling free of the wood. This is the dilemma that many homeowners face with their toilets. Toilets often become loose and wobbly over time, and this can cause the toilet gasket to become broken and leaky. In most cases, it is not necessary to replace the entire floor. Replacement of the wood screws into different areas of the metal plate and a new toilet gasket will typically fix the problem.
Time itself can also be the enemy of the gasket. The wax can dry and become brittle over many years, leading to leaks. This type of leak may not show itself around the toilet's base—it may be found in the basement leaking from the sewer pipe. The replacement method is the same, with the most important step in any replacement being the total removal of all of the existing wax prior to setting the new gasket in place.