If your toilet is overflowing, lift the tank lid and press the flapper down over the drain hole, then turn the supply valve behind the toilet clockwise until it stops. Once the bowl drains, plunge the clog or reach for a toilet auger.
An overflowing toilet is a bathroom floor problem first and a plumbing problem second. The water climbing toward the rim comes out and can quickly turn into a mess on your bathroom floor if you do not stop the flow. In most cases, the issue starts with a clog. However, repeated overflows can point to a larger plumbing issue. One leaking toilet can waste up to 200 gallons a day.
This guide walks through the immediate steps, the fixes that work, and the signs that mean it’s time to put down the plunger and call a plumber.
What Should You Do the Second a Toilet Starts Overflowing?
An overflowing toilet can soak a bathroom floor in minutes, so what you do first matters most. Work through these steps in order to stop the water, clear the bowl, and keep the damage contained.
- Stop the water at the tank: Speed matters here. Pull off the tank lid and set it somewhere safe. Reach in and press the flapper, the rubber disc at the bottom of the tank, down over the drain hole. Water stops draining into the bowl.
- Find the supply valve: It sits on the wall or floor behind the toilet, usually on the left. Turn it clockwise until it stops. The fill valve can no longer pull in fresh water. Stuck valve? Lift the float instead. Holding the float ball or float cup up tells the fill valve the tank is full.
- Plunge: Once the water level drops a bit, seat a flange plunger over the drain hole and work it. Flush just once.
- Contain the water on the floor: Towels first, then a wet-dry vacuum if you own one. Water that sits on a bathroom floor for a few hours works its way under tile, into the subfloor, and through the ceiling below. Mold can start growing on damp material within 24 to 48 hours, so drying the floor the same day is worth the effort.
- Do not flush again: A second flush sends another tank of water into a bowl that has nowhere to put it. Leave the bowl water alone. A partial clog will drain slowly on its own. Run the exhaust fan or open a window.
Why Is My Toilet Overflowing?
An overflow means water is entering the bowl faster than it can leave. Three things can cause that.
A clogged toilet or drain
Most toilet overflows start with a clog. Too much toilet paper, a foreign object, or even wipes labeled flushable can jam the trap behind the bowl. The water level rises with each flush. A clogged toilet may make gurgling sounds or drains slowly for a day or two before it overflows.
A fill valve or float that will not shut off
If water pours into the bowl when nothing has been flushed, the tank components may be the problem. The float mechanism tells the fill valve when to stop filling the tank. When the float sits too high or sticks, water can climb past the overflow tube and run into the bowl nonstop. A cracked overflow pipe or a flapper without a proper seal does the same thing. One clue of this problem happening is water trickling into the bowl at a steady rate with no clog anywhere.
A sewage backup or sewer line problem
Sometimes the toilet is not the source of the problem. A blockage in your home’s sewer line can cause backups through the lowest drains. If several drains in the house are slow, if the shower gurgles when you flush, or if dark water comes back up, the blockage is downstream. Tree roots, a collapsed section of pipe, or soil movement can all block a sewer line.
Toilet Problem Causes and When to Call a Plumber |
||
|---|---|---|
| Symptom | Likely cause | Handle it yourself? |
| Water rises, then drains slowly | Clog in the trap | Yes. Plunge or auger. |
| Water runs into the bowl nonstop | Float or fill valve | Yes. Adjust the float. |
| Toilet overflows when the shower runs | Sewer line blockage | No. Call a plumber. |
| Dark water or a sewage smell | Sewage backup | No. Call a plumber. |
| Overflow repeats every few weeks | Deeper clog or line damage | Call a plumber. |
How Do You Clear a Clogged Toilet at Home?
Plunge it the right way
Use a flange plunger, the kind with a narrower lip inside the rubber cup. Seat the flange in the drain hole and push down slowly to get a seal. Then work it. Slow push, fast pull, ten to fifteen strokes. The pull does more than the push because it drags the clog back toward you. Flush once to test.
Try dish soap and hot water
No plunger in the house? Squeeze a half cup of dish soap or any liquid soap into the bowl, then pour in a bucket of hot tap water. Not boiling. Boiling water can crack porcelain. Give it twenty minutes. The soap slips between the clog and the pipe wall and loosens it enough to move.
Use a toilet auger
A toilet auger, sometimes called a toilet snake, reaches around the trap where a plunger cannot. Rest the curved guard against the bowl, feed the cable in, and crank the handle. Pull back when you hit resistance. A general drain snake will scratch the porcelain, so stick with an auger made for toilets. If the auger comes back empty and the water still will not drain, the clog is farther down the line than the tool can reach.
Quick tip: Skip chemical drain cleaners. They sit in the bowl, eat at the wax seal, and make the job harder for whoever opens the toilet next.
How Do You Fix a Toilet That Keeps Running or Overfilling?
Adjust the float and the water level
Remove the lid and watch a full fill cycle after a flush. The water should stop about an inch below the top of the overflow tube. Most modern toilets have a float cup on the fill valve with an adjustment screw or clip. Turn the screw counterclockwise to lower the level. Older tanks, sometimes called a toilet cistern, use a float ball on a metal arm. Bending the arm down slightly can help the valve shut off sooner.
Check the flapper and flush valve
A worn flapper lets water leak out of the tank and into the bowl, and the fill valve refills it over and over. Press the flapper down with your finger. If the running stops, the flapper needs replacing. If the flush valve seat underneath is pitted or rough, a new flapper will not hold either, and the flush valve assembly has to come out.
Replace a failing fill valve
A fill valve that makes a hissing sound, fills slowly, or shuts off at random may have reached the end of its life. Replacement takes about half an hour with the water supply off. Universal fill valves fit nearly every modern toilet.
When should you call a plumber?
A plunger and a float adjustment solve most toilet problems. Call a licensed plumber when you see any of these:
- The toilet overflows again within a few days of the last quick fix.
- Other drains are slow, or the tub fills when you flush.
- Sewage or dark water comes up into the bowl or the shower.
- Water pools at the base of the toilet, which points to a failed wax ring rather than a clog.
- You have plunged, augered, and adjusted the float, and nothing changed.
Lasiter and Lasiter: Your Partner for Toilet Overflows and Drain Cleaning
Figuring out why a toilet keeps overflowing is easier with an experienced plumber. Lasiter and Lasiter Plumbing has been working around the Fort Worth area since 1974, and our service plumbers came up on the new construction side. They understand how a home’s whole plumbing system was laid out, not only the fixture in front of them. We handle toilet repair, drain cleaning and clog repair, and sewer line problems.
We do not quote plumbing work over the phone. We come look at the toilet, run a camera down the line if the overflow keeps coming back, then give you a number we stand behind.
Call today or request a free estimate online. If the water is already on the floor and will not stop, our 24-hour emergency service is available.
Frequently Asked Questions
Can I flush an overflowing toilet to clear it?
No. Flushing sends another full tank of water into a bowl that cannot drain. Stop the water first, then plunge or auger once the bowl level drops.
Why does my toilet overflow when I run the shower or washing machine?
That points to a blockage in the main sewer line, not the toilet. Water from other fixtures has nowhere to go and backs up through the lowest drain in the house, which is often the toilet. This one needs a plumber with a camera.
Should I use a chemical drain cleaner on a clogged toilet?
Skip it. Chemical cleaners sit in the toilet bowl, damage the wax seal, and rarely reach a clog in the trap. A flange plunger or toilet auger does the job without the risk.
