Stop the water first
The water in the bowl comes from the tank. Pressing the flapper — the rubber seal at the bottom of the tank — back onto its seat stops more water from entering the bowl. Then close the supply valve on the wall behind the toilet.
- Turn the oval valve handle clockwise until it stops
- If the valve is stuck, close the main shutoff for the house
- Put towels down; bowl water from a clog is usually clean, sewage backup is not
One toilet, or the whole house?
Check the tub and the lowest floor drain. If only the toilet is affected, it's a clog in the toilet or its short drain run. If water rises in the tub when the toilet is flushed, or several drains are slow, the blockage is further down in the main line, and more flushing will push sewage into the house.
Clearing a toilet clog
Use a flange plunger — the kind with a soft sleeve that seals into the drain opening — with steady, firm strokes. A closet auger reaches clogs a plunger can't. Avoid chemical drain cleaners in toilets; they rarely work on toilet clogs and make the water hazardous to anyone who has to clear it.
When to call a plumber after an overflow
Call if the toilet clogs repeatedly, if water rises in other fixtures, if you see sewage, or if the toilet rocks or leaks at the base after the overflow. A toilet that clogs every week usually points to a drain line problem, and a base leak means the wax seal needs replacing.
When the overflow isn't the toilet's fault
If a toilet overflows when you run the sink, shower or washing machine, or several fixtures back up at once, the clog is in the main drain or sewer line. Stop using water in the house and call a plumber, because plunging won't reach it and more water only adds to the backup.
Toilet Overflowing? What to Do Right Now: when to call a pro
- Water on the floor at the base
- Toilet clogs and other drains are slow too
Toilet Overflowing? What to Do Right Now: common questions
Is toilet overflow water dangerous?
Water from the bowl is contaminated. Wear gloves, clean hard surfaces with a disinfectant, and remove soaked carpet pad or drywall rather than drying it in place.
Why does my toilet keep clogging?
Common causes are low-flow toilets from the 1990s, a partial blockage in the drain line, or items like wipes that don't break down. A recurring clog is worth a plumber's inspection.
How do I stop a toilet from overflowing?
Lift the tank lid and push the flapper down, then turn the shutoff valve behind the toilet clockwise. If there's no valve, lift the float to stop the fill.
When is an overflowing toilet a sewer problem?
If water rises in other drains, or the toilet overflows when other fixtures run, the main line is likely blocked.
Every home differs; editorial standards.