A water leak coming from the base is definitely a common problem that a toilet can experience. However, a clog inside the toilet will not cause it. Toilets have a wax seal underneath which would have to malfunction before a leak from the base appears. A clog will show its presence in other ways.
Toilet Clog Symptoms
If a toilet is clogged, the water will not leak from underneath the toilet. Toilet clogs basically alert you with noticeable, straightforward symptoms. Instead, it will fill the bowl until it spills out over the sides if the clog is not removed. A toilet that is only partially clogged will exhibit either a sluggish flush or a partial flush, not completely removing everything from inside the bowl. A sluggish flush may not even indicate a clog inside the toilet. The actual location of the clog could be further along in the pipe system and affect the toilet.
Leaks From Base
If you discover water around the base of the toilet and you know that it was not caused by the bowl overflowing, the cause is the wax ring, which acts as a seal not only for water but also for sewer gas. If the water leak from the toilet base is accompanied by the unpleasant, sometimes overpowering odor of sewer gases, you can be certain the wax ring is not properly sealing the space between the toilet and the flange. The flange rests on top of the drainpipe that rises up to the bathroom floor underneath the toilet.
If you have a toilet clog, do not flush the toilet in hopes that you can force the clog down through the drain, which will only lead to an overflowing bowl. The two tools that are specifically designed to remove toilet clogs are a toilet plunger and a closet auger. The plunger is effective on shallow clogs inside the toilet drain while the auger, commonly referred to as a "snake," can reach deeper clogs.
Repairing Base Leaks
To repair a leak from the base of the toilet, you need to remove the toilet and install a new wax ring. These items are easily replaceable and can be obtained from a home improvement or hardware store. A standard, universal wax ring will fit all floor-type toilet bowl. Turn off the water supply to the toilet at the shutoff valve behind the toilet's left side or at the main water shutoff outside. Empty all the water from the tank and bowl before lifting the toilet.