Toilet overflowing and will not stop

A toilet that is overflowing is loud, wet, and fast, and the instinct is to flush it again to make it go down. Do not. The bowl is full because the water has nowhere to go, and another flush adds gallons on top. Stopping the water takes about ten seconds and no tools, and most overflowing toilets clear with a plunger once the level is under control.

Stop the water in ten seconds

The water pouring into the bowl is coming from the tank. Stop the tank and you stop the overflow.

1. Lift the tank lid and set it somewhere it will not break.
2. Push the flapper down. The flapper is the rubber disc at the bottom of the tank, on a chain. Press it closed with your hand. The water into the bowl stops. Tank water is clean; it is the same water that comes out of the sink.
3. Close the supply valve. The small oval or football-shaped handle on the wall or floor behind the toilet, turned clockwise until it stops. Now nothing is going into the tank or the bowl.

If the bowl is right at the rim, leave it. It cannot overflow further without more water going in, and a partial clog often lets the level drop on its own over ten or twenty minutes.

Clear the clog

• Wait for room to work. A bowl at the rim slops over when you plunge. Bail some water into a bucket with a cup if it is not dropping on its own.
• Use a flange plunger, the kind with the rubber sleeve at the bottom that fits into the drain opening, not the flat sink plunger. Push gently the first time to get the air out, then work it firmly, straight down and up, for a dozen strokes.
• Check before you flush. Open the supply valve, let the tank fill, and if the bowl has drained to its normal level, flush once with your hand ready on the flapper. If the level starts rising instead of swirling, push the flapper closed again.
• A toilet auger is the next step: a short crank-handled cable made for toilets, with a sleeve that protects the porcelain. Feed it in until it stops, crank, and pull back. It reaches what a plunger cannot, usually in the trap of the toilet itself.
• Never chemicals. Drain cleaner in a toilet does not work on what clogs toilets, it damages the wax seal and old cast iron, and it makes the bowl dangerous to plunge.

The only things that belong in a toilet are toilet paper and what the body produces. Wipes marked flushable, paper towels, feminine products, and cat litter are what comes out of toilets and the lines behind them.

Why it keeps overflowing

If the same toilet overflows again a day or a week later, it is telling you something.

• Other fixtures gurgle, or a shower fills when you flush. This is not the toilet. The main drain line is partly blocked, and the toilet is the first fixture to show it because it sends the most water at once. Stop using water in the house and treat it as a main line problem.
• The flush is weak even when it works. Mineral scale in the rim jets and the siphon jet, common in our hard water, cuts the flush down until it cannot carry solids through the trap. A vinegar soak and a stiff wire in the jets help; a badly scaled old toilet is usually replaced.
• An object is in the trap. A child’s toy, a toothbrush, an air freshener clip. The toilet keeps half-clogging on ordinary paper until it is pulled and the object is removed from underneath.
• A cast iron closet bend under the slab in a pre-1975 home, rough and channeled inside, catches paper that a smooth pipe would carry away.

Cleanup and sanitation

Water that came out of a toilet bowl is sewage, even if it looks clear. Keep children and pets out of the bathroom until it is done.

• Gloves on. Towels down across the doorway to stop water running into the hall and, in a slab home, under the baseboards of the next room.
• Bail or wet-vac the standing water. Towels that touched it go in the wash on hot, by themselves, or in the trash.
• Wash the floor and the base of the toilet with hot soapy water, then a disinfectant left on for as long as the label says. Get the grout lines and the toe kick of the vanity.
• Water that ran under a vanity, into carpet in an adjoining room, or through a ceiling to the room below has gone where you cannot clean it, and that is a call to a remediation company, not a mop.

The brittle valve behind the toilet

In a house built before about 2000, the supply valve behind the toilet may not have been turned in twenty years. The stems on older multi-turn valves seize, the packing dries out, and the plastic handle on some 1980s and 90s valves cracks in your hand. If the valve will not turn with normal hand pressure, stop. Forcing it can snap the stem and turn an overflow into a spraying supply line. Push the flapper closed instead, then go close the main shutoff for the house.

That valve is worth replacing with a quarter-turn ball valve while a plumber is there, and so are the old supply lines to every toilet and sink in the house. A failed toilet supply line is one of the most common causes of a flooded home in Florida, and it fails whether you are home or not.

When to call

Plunging and an auger are yours. Call when the toilet overflows a second time with no obvious cause, when anything else in the house gurgles or backs up while it happens, when the supply valve will not close or is leaking, when there is water in a room below, or when you know something other than paper went down. A toilet that keeps clogging usually has a specific reason, and finding it is a short visit with a camera or a wrench.

Tell us what the toilet does, whether other drains react to it, how old the house is, and whether the supply valve turned. That is usually enough to know whether it is the toilet, the line, or the valve, and what to bring.