After flushing the toilet, watch the water to ensure that it goes down and also that the valve completely refills the bowl and tank. If it looks like the toilet will overflow, take the tank lid off immediately. Lift the float device upward. This is often a plastic gray or black piece, and it may be located near the handle. Doing this shuts off the water to the tank. Continue to hold it to avoid further clogging. Turn off the supply valve below the toilet until the clog has been cleared.
Inspect the supply, flush and fill valves twice each year. Also, look at the supply line. Be sure that the supply line can be turned off easily if necessary. For older valves that have screw mechanisms, it may be harder to turn them off. If these are leaking, they should be replaced. It is better to replace them with a simple ball valve, which is easier to turn off quickly.
Another way to prevent water damage under the floor is to keep the toilet caulked around the bottom. Water can seep under the floor from a slow leak, condensation or an overflow. For those who own a condominium, such water damage can spread to a neighbor’s ceiling below and cause some costly problems. To learn more about water damage from toilets and other plumbing fixtures, discuss your concerns with an agent.