Toilet Overflowing: Stop It in 10 Seconds, Then Clear It

Toilet overflowing: what to do right now

Short answer

Take the tank lid off and push the flapper down to stop water entering the bowl, then turn the shutoff valve behind the toilet clockwise. Once the water stops rising, clear the clog with a flanged plunger. If other drains back up too, the clog is in the main line and plunging won't fix it.

Stop the water

Push the flapper closed
Lift the tank lid and press the rubber flapper at the bottom of the tank down onto its seat. The bowl stops filling immediately.
Close the supply valve
The oval or round handle on the pipe behind the toilet, turned clockwise. If it's seized, lift the float arm or fill valve float to stop the refill and hold it while someone closes the main shutoff.
Don't flush again
Each flush adds a tank of water to a bowl that can't drain.

Clearing the clog

Use a flanged plunger
The kind with a fold-out sleeve that fits the bowl opening. Push gently first to remove air, then use firm strokes with a good seal.
Try a closet auger
A toilet auger has a protected bend that won't scratch porcelain. Feed it in, crank, and pull back.
Skip chemicals
Drain openers rarely clear a toilet clog and leave caustic water in the bowl for whoever works on it next.

Is it the toilet or the main line?

If Only this toilet is affected: The clog is in the toilet's trap or branch line. Plunging or an auger usually works. If it keeps happening, see toilet repair.
If Water comes up in the tub or shower when you flush: The main line is blocked downstream of both. Stop using water and call. See drain backing up.
If Several toilets or a floor drain back up: Main line or sewer problem. Call for drain cleaning.

Cleaning up safely

Overflow water from a toilet bowl can carry bacteria. Wear gloves, disinfect hard floors, and launder or discard soaked bath mats. Water that ran under vinyl or into a subfloor, or through the ceiling below, needs drying out promptly to prevent mold and rot.

When to call a plumber

Plunging and an auger don't clear it.
Other fixtures back up when the toilet is flushed.
Something solid, like a toy or phone, went down; pushing it further can lodge it in the line.
The toilet overflows often, even with normal use.