Short answer
If a toilet is overflowing, do not flush again. Stop the water by closing the shut-off valve behind the toilet or lifting the float inside the tank. Then try a flange plunger, then a closet auger. Skip chemical drain cleaners. If other drains are slow or water keeps coming, the problem may be the main line or the septic system, so call a plumber.
Do this first
- Do not flush again. Florida Atlantic University's housing guide says never to flush when the water is above its normal level and not draining, because the contents can spill onto the floor.
- Stop the water. Turn the toilet's shut-off valve, usually on the wall or floor behind it, clockwise until it stops. Plumbing guides also say that if you cannot reach it, you can take the lid off the tank and lift the float so the tank stops filling, and prop it up. If water still rises, close the main water valve for the house.
- Mind the electricity. If water is spreading toward outlets or appliances, do not stand in it and touch anything electrical. The CDC says to switch power off only from a dry spot and to call an electrician if you cannot reach the panel without entering water.
- Protect your hands and the room. Put on rubber gloves. Close the bathroom door and put towels at the bottom of the door to hold water in.
- Check the other fixtures. Look at nearby sinks, the tub and any floor drain. If they are slow or gurgling, or water is coming up elsewhere, stop using water and see the section on multiple fixtures below.
- Plunge or use a closet auger only once the water is off and the bowl is not about to overflow.
- Clean and disinfect with gloves, then wash your hands.
How to stop a toilet overflowing: the shut-off valve and the float
An overflow often starts when a clog stops the bowl draining while the tank refills, or when the tank keeps filling after a flush. Cutting off the supply stops new water entering. It does not remove water already in the bowl.
- Shut-off valve. Look for a small valve near the floor or wall behind the toilet. Turn it clockwise until it stops. If it is stuck, do not force it hard enough to break it.
- Float in the tank. Lift the tank lid and raise the float lever, ball or cup, then hold or prop it so the tank stops filling. Plumbing company guides describe this as the fallback when there is no working valve.
- House main valve. If neither works, close the main valve where the water enters the house. See our burst pipe guide for finding it.
If the overflow continues after the water supply is off, the water may be coming back up the drain, which can mean a blockage further down the line or a sewage backup. In that case stop using water and see sewage backup: what to do.
Toilet clogged: what is safe to try
For a single clogged toilet, two tools are the standard homeowner steps.
1. A flange plunger
Florida Atlantic University's guide describes the method: set the plunger slowly into the bowl so it covers the opening at the bottom, then pump up and down, slow at first and then faster. It may take several tries. Wear gloves and expect splashes, so keep towels ready.
2. A closet auger
A closet auger, sometimes called a toilet snake, is a short hand-cranked tool made for toilets. Plumbing guides describe feeding it into the drain, cranking until you meet the clog, then cranking back to pull it free, and then plunging again. Go gently so you do not scratch the bowl. Our drain snake guide explains snakes for other drains, but a closet auger is the tool for a toilet.
If both fail after a few honest attempts, stop and call a plumber rather than forcing it. For other drains in the house, see clogged drain: what to try yourself and when to call a plumber.
What not to do with a clogged toilet
- Do not keep flushing. It adds water to a bowl that is already not draining (Florida Atlantic University).
- Do not use chemical drain cleaners. The University of Florida's extension fact sheet on clogged drains calls them toxic and caustic, says they could burn you or damage pipes and fixture finishes, are helpful only for sluggish drains, and are bad for septic tanks. It warns never to mix products and not to use a plunger after chemicals. The EPA's septic guidance also says to avoid chemical drain openers.
- Be cautious with in-tank cleaners. New York City's environmental protection department warns they can corrode the rubber parts of a flapper.
- Do not flush wipes, even flushable ones. Florida Atlantic University says so-called flushable wipes do not break down like toilet paper. Put menstrual products and paper towels in the trash.
- Do not use bleach with ammonia, or any mix of cleaners, in the bowl or on the floor.
Toilet won't flush or keeps clogging: general causes
One clog after something unusual went down the toilet is a different problem from a toilet that clogs again and again. For a toilet that keeps clogging, common general causes are:
- Things that should not be flushed. Wipes, paper towels, sanitary products and diapers are repeatedly named by the EPA, Seattle Public Utilities and the City of Northville as causes of blockages. The EPA says only human waste and toilet paper belong in a toilet.
- A partly blocked drain line beyond the toilet. Seattle Public Utilities names tree roots, grease buildup and flushed objects as common reasons for a blocked private sewer line. A toilet may be the first fixture to show it. See tree roots in sewer lines.
- A septic system problem. A full tank or a struggling drainfield can slow every fixture. See signs your septic system is failing.
- A flush mechanism problem. If the bowl water looks normal but the handle does nothing, the issue is probably in the tank, which is a different repair from a clog. A plumber can sort this out.
If a toilet clogs repeatedly, ask a plumber to look past the toilet, ideally with a camera on the line once it is clear. Seattle Public Utilities advises asking for the probable cause of a blockage in writing and for a copy of any inspection video.
When more than one fixture is affected: main line or septic
A single toilet is usually a local problem. Several fixtures at once suggest the shared drain. Seattle Public Utilities describes a backup as usually caused by something blocking the sewer pipe, and recommends calling a plumber and then the utility. Watch for:
- Gurgling in drains when the toilet flushes. See gurgling drains and toilets.
- Water or sewage coming up in the tub, shower or a basement floor drain.
- Slow drains across the house, or a smell. See sewer smell in house or yard.
- The same problem returning after being cleared.
If you are on a city sewer, the blockage may be in your private line or in the main. Learn where each part runs in main sewer line location and sewer cleanout and sewer cleaning. If you are on septic, call a septic professional and see what not to flush with a septic system. The EPA notes a single leaky or running toilet can add as much as 200 gallons of water a day to a septic system, so fix leaks promptly and avoid using a lot of water while a problem is open.
Cleanup and hygiene after a toilet overflow
Treat overflow water as contaminated. The City of Northville's sewage guidance says to treat all water-soaked surfaces and items as contaminated until properly cleaned and sanitized, and public health sources say to avoid skin contact, keep cuts covered and wash hands often.
- Wear rubber gloves, rubber boots if the floor is wet, and goggles if splashing is likely. The CDC lists rubber boots, rubber gloves and goggles for sewage.
- Soak up water with towels or a mop, and keep children and pets out until the area is clean.
- Wash hard surfaces with hot water and detergent first. The CDC recommends this for floors, fixtures and counters. Then disinfect following the product label. Do not mix bleach with ammonia.
- Wash soiled towels and clothes in hot water with detergent, separate from other laundry (CDC).
- Wash your hands well afterward, and before eating.
- The EPA says to dry water-damaged areas within 24 to 48 hours to prevent mold. Check under the toilet and along the baseboard, and ask a professional if water reached carpet, subfloor or ceilings below.
- Take photos if there is damage and tell your insurer. Policies differ, so ask what they require.
When to call a plumber
- The overflow continues after the water supply is off.
- The plunger and closet auger do not clear it.
- More than one fixture is slow, gurgling or backing up.
- The toilet clogs again soon after being cleared.
- You are on septic and suspect the tank or drainfield.
- Water has reached walls, ceilings below or electrical equipment. Use an electrician or emergency services for electrical hazards.
To find and vet a company, see drain cleaning near me: how to find and vet a company. Get a written scope and ask what the plumber found.
What to look up where you live
- Your sewer utility or city public works: where the public pipe ends and yours begins, and how to report a backup.
- County health department or environmental health office: for sewage in the house or yard, and septic questions.
- State or provincial plumbing or contractor licensing board: to confirm a plumber's licence and check complaints.
- Your insurance agent: what to document if an overflow damages floors.
For Canadian readers. Plumbing is regulated by each province or territory, and municipalities set their own rules for sewer connections. Check your provincial regulator and your city. Costs are in Canadian dollars and cannot be compared directly with US figures.
For plumbing, drain and septic company owners
A toilet overflow is a high-urgency, high-intent search, and the callers want a company that answers and says what it will do. Read emergency plumber marketing and drain cleaning marketing, or book a call with LiveLeadsLane. LiveLeadsLane is a marketing practice for contractors, not a directory, and it does not take jobs or refer homeowners.
