6 Reasons Why Your Toilet Won’t Flush

Stephanie Carwell - 07/23/2023

A toilet that won’t flush can be an embarrassing inconvenience, but it is generally easily fixed! Don’t be afraid to take the tank lid off of your toilet and look around – oftentimes you can diagnose and correct the problem without needing to call a plumber.

In this article, we will examine six common reasons why your toilet won’t flush and guide you through fixing these issues. If after trying these you’re still having trouble, then it’s probably the time to contact a professional plumber.

Low Water Level

Your toilet needs enough water in the toilet tank in order to flush properly. If the water level is too low, the toilet won’t flush well, if at all.

Checking the water level is easy – simply remove the lid of your toilet cistern and look to see how full the tank is after the fill mechanism shuts off. Generally, the tank will have an easy to see stain that shows where the water level has been. If your tank is not able to reach this level then the tank may not have enough water. This can be due to a variety of reasons, including a leaky flapper or an issue with the fill valve. Try adjusting the float that controls the fill valve to raise the water level. If that doesn’t work, you may need to replace the fill valve.

Clogged Toilet

A clog is the most common reason for your toilet to stop flushing. Blockages can be caused by flushing inappropriate items, using too much toilet paper, build-ups in the toilet’s drain trap, or a blocked plumbing vent. While blocked plumbing vents will likely require help from a licensed plumber, your run-of-the-mill blockage can usually be fixed with a plunger.

Note: Avoid flushing paper towels, tampons, and even so-called ‘flushable’ wipes to avoid clogs.

How to correctly use a plunger:

Most people aren’t using their plungers right! Here is a quick guide on using a plunger:

Use the Right Plunger: For toilets, a flange or toilet plunger is best. It has an extra piece of rubber (the flange) at the bottom to create a better seal.
Prepare the Toilet Bowl: If the bowl is empty, add enough water to submerge the plunger head. If it’s too full, scoop out excess water.
Position the Plunger: Insert the plunger into the bowl and position it over the drain hole. Ensure the plunger completely covers the hole and that there’s enough water to create a seal.
Use a Pumping Action: With the plunger securely in place, apply downward pressure to compress the plunger, then pull up sharply to disturb the clog. Keep the seal intact during this motion. Repeat about 15-20 times or until the water starts to drain.
Check Your Progress: After several pumps, quickly pull the plunger off the drain to create extra suction. If the water flows out, you’ve successfully cleared the clog. If not, repeat the plunging action.
Flush the Toilet: Once the clog is cleared, flush the toilet to make sure everything is flowing properly.

If your toilet clog isn’t fixed after plunging then your problem may require professional plumbing services. More serious blockages require a toilet auger – and while there are DIY augers available, fixing a clog deep within your sewer line is generally best left to the experts.

Toilet Flapper or Fill Valve Problem

The flapper, also known as the flush valve seal, and the fill valve are crucial components of your toilet. The flapper creates a seal within the tank, letting the tank fill with water. When the toilet is flushed, the flapper lifts to allow water into the bowl. If the flapper is worn or damaged, it may not lift correctly, leading to a weak flush. Similarly, a faulty fill valve can prevent the tank from refilling properly after a flush. In both cases, the faulty part should be replaced. Flapper valve replacements are available at your local hardware store and installing a new one is a quick and easy job that requires no special tools or skills.

Replacing fill valves is slightly more involved, but is often a task that homeowners can handle themselves. If you don’t feel comfortable replacing the fill valve, your local plumber will be happy to help.

Toilet Handle Trouble

Sometimes, the cause of your toilet not flushing is as simple as a loose or broken toilet flush handle. If the handle is too loose, it may not lift the flapper enough to start a flush. If it’s broken, it may not lift the flapper at all. Tighten the nut inside the tank that secures the handle (remember, it’s usually reverse-threaded), or replace the handle if it’s broken or worn out.

Another common problem related to the toilet handle is a slipped lift chain. This chain connects the end of the toilet handle arm to the flapper valve. Check to see that this chain is still attached, and if it has fallen off simply reattach it.

Damaged or Misaligned Float

The float in your toilet tank controls the fill valve and consequently the water level. If it’s damaged or not set correctly, it may not rise and fall correctly, leading to improper filling of the tank. A replacement may be necessary if adjusting the float doesn’t rectify the problem.

How to adjust your toilet float

Adjusting a Ball Float:

Locate the float ball, which is a large plastic ball attached to a horizontal rod (float arm).
Find the screw at the end of this rod. This is the adjustment screw.
Using a screwdriver, turn the screw counter-clockwise to raise the water level or clockwise to lower the water level.
After adjusting, flush the toilet to check the new water level. You might have to adjust the screw a few times to get the right water level.

Adjusting a Cylinder Float:

Locate the float cylinder, which moves up and down along a vertical fill tube.
On the top of the float cylinder, there will be a spring clip connecting it to a metal rod (the float adjustment rod).
Pinch the spring clip and slide the float cup up to raise the water level or down to lower the water level.
After adjusting, flush the toilet to check the new water level. Adjust it until you reach the optimal water level.

Blocked Inlet Holes

The small holes under the rim of your toilet bowl are known as inlet holes or rim jets. These allow water to flow into the bowl when you flush. Over time, they can become blocked with mineral deposits, especially in areas with hard water, causing a weak or slow flush.

Fixing blocked inlet holes:

Prepare a vinegar and water solution: Mix equal parts hot water and white vinegar. You’ll need around two cups of this solution.
Turn Off the Water Supply: Locate the water supply valve of the toilet and turn it clockwise to shut it off.
Flush the Toilet: Flush the toilet to remove as much water as possible from the tank and bowl.
Plug the Inlet Holes: Roll up pieces of toilet paper or use packing tape and plug the inlet holes.
Apply the Vinegar Solution: Pour the hot water and vinegar solution into the overflow tube in the toilet tank. The solution will then move from the tank and into the toilet bowl through the blocked inlet holes.
Let it Soak: Allow the vinegar solution to sit for at least an hour. The acidity of the vinegar helps dissolve the mineral deposits blocking the inlet holes.
Remove the Plugs: After soaking, remove the toilet paper or tape plugs from the inlet holes.
Turn on the Water Supply: Open the water supply valve and let the tank fill.
Flush the Toilet: Flush the toilet a few times to rinse away any remaining vinegar solution and dislodged mineral deposits.

If this doesn’t solve your problem then there may be another issue with your plumbing system and you will want to contact a professional.

Resolving Common Toilet Flushing Issues

While a toilet that won’t flush is a nuisance, it is often a problem that can be easily fixed. Identifying the underlying issue is half the battle. From low water levels and clogs to damaged parts or blocked inlet holes, the solutions range from simple adjustments to part replacements. Armed with this knowledge, you can tackle your toilet troubles with confidence.

Remember, if the problem persists or you’re uncomfortable performing these tasks, don’t hesitate to call a professional plumber.

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