Often you can set the water level by adjusting the float. Toilets with ball floats and arms usually have adjustment screws or dials to raise or lower the arm. If your toilet mechanism has a cylinder float, squeeze the float clip to release the float so you can slide it up or down to the correct level.
Start with a plunger to address any potential clogs, and if that doesn't work, check the tank's flapper valve, float, or fill valve for any issues and make necessary adjustments or replacements.
Usually, we think of a clogged toilet overflowing. However, the opposite can also happen where the blockage siphons water out of the bowl. Obstructed plumbing means that water cannot flow freely and circulate to the toilet. As a result, the water level in the tank will drop.
If your toilet is overflowing and you can't get the shut-off valve to budge, your next stop should be to check the flapper. Remove the tank lid and look for a hinged rubber disc covering a hole at the bottom. If that disc (flapper) is open, reach in and close it manually. This should stop the flow of water.
If there's a lot of water in the bowl, scoop some of it out with a bucket or bowl. If the water level is too high, it will completely overflow when you submerge the plunger. You only need to take out a little bit to make space.
Check your water levels
Low water levels in your tank are common causes of toilets filling up with water when flushed. They can also cause slow-draining toilets. You can manually top up your tank with water to help the flush. Then, check the flush tube for cracks and bends that lead to leaks.
Fill a bucket with hot, but not quite boiling water and pour it directly into the drain. The combination of heat and pressure can sometimes be enough to clear minor blockages such as soap scum build-up.
Plunge the Water
Shut off the water supply valve. Place the flange of a toilet plunger firmly into the drain hole in the bottom of the toilet bowl. Plunge with an up-and-down motion to remove most water from the bowl. This should also force out any clog.
Generally, a toilet overflow stems from plumbing issues like a clogged drain or a blocked plumbing vent. A common culprit is a stubborn blockage in the drain line, usually caused by items flushed that shouldn't be, like wipes or excessive toilet paper.
If your toilet is weak or won't flush entirely, you might have a damaged toilet flapper that isn't sealing. The flapper should form a tight seal between the tank and the bowl. If it's cracked, warped or damaged, the water will trickle into the bowl, and the toilet can't perform a powerful flush.
It depends on the clog. Blockages consisting of water-soluble materials can sometimes fix themselves if you give them enough time. Substances like toilet paper and fecal matter will eventually dissolve within the toilet drain and clear the clog organically.
One of the strongest substances for unclogging a toilet is a commercial drain cleaner specifically designed for toilet clogs. These cleaners typically contain powerful chemicals that dissolve organic matter and stubborn blockages.
“Look for a screw head on the valve that controls the float and that controls the water level,” Siv says. Adjust the water level by turning the screw clockwise to lower the ball or counter-clockwise to raise it. Only turn the screw one rotation at a time, then flush the toilet to see if it works efficiently.
Directly on top of the fill valve should be a single screw. Turn this screw clockwise or counterclockwise 1 full rotation. Clockwise will raise the water level and counterclockwise will lower it. Avoid turning the screw more than 1 full rotation at a time.
An overflowing toilet is caused by one of three things: a clogged or blocked drain that doesn't allow for a proper flush, an improperly adjusted float that allows the tank to overfill or a blocked vent pipe that replaces the air in the pipe after each flush.