Wax toilet rings are added to most toilets in order to create a seal between the bathroom and the pipes that lead to the sewer or septic tank. It is important that this ring remain sealed correctly to prevent leaks and sewer gas seepage.
If there is water on the floor around the toilet, or foul smells in the bathroom, the wax ring may need to be replaced. Lift the toilet and add the new ring. It is a job for an experienced do-it-yourselfer.
Funnel or No Funnel
Some wax toilet rings come with a plastic funnel to further prevent leaks. A funnel may restrict the flow of water, but it is ultimately a matter of personal choice.
Flange, Pipe, and Bolts
The flange and bolts may be broken. In this case, replace them. A section of pipe may need to be replaced also. The old wax ring will need to be scraped from the flange.
Height and Width
A correctly sized ring is necessary. Locate the toilet manufacturer's model number. This information may be on the inside of the tank or underneath it. Measure the pipe opening in the floor. Talk to someone at the hardware store to get the right size. Wax rings come in varying thickness and height. If the floor has been built up and a standard size isn't high enough, use a thicker one. Some people say to use 2 rings to ensure that there is enough wax to form the seal; others disagree.
Handling the Ring
The wax is very sticky. Try not to handle it directly. Place it either over the flange or around the horn on the bottom of the toilet. If it's on the flange, it may be harder to keep it in place while the toilet is lowered. If the ring is squashed by the toilet, it's better to start over with a new ring.
PVC flanges are a viable alternative to wax rings. The seal can be adjusted until it is tight against the sides of the pipe. Some people like this alternative; other swear by tried and true wax ring.