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Toilet Flushing Slow: 4 Common Reasons and Fixes

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If you've noticed your toilet flushing slower than it should, the problem isn't just annoying, it could actually lead to a clog or something even more serious. There are a number of reasons your toilet isn't flushing as effectively as it once was, some are easy fixes and others are more complex.

This article will cover the most common reasons your toilet is flushing slow and provide you with the information you need to fix the problem.

Toilet bowel with a slow flush

 4 Reasons Your Toilet Flushes Slow

A slow flushing toilet won't do a good job of removing waste, which can be unhygienic and embarrassing. It's also a sign of a bigger problem. These are the four most common reasons your toilet will flush slow and steps on how to fix the problem.

Low Water Level

The most common reason a toilet will slowly flush is due to a low water level within the tank. When the water in the tank is released into the toilet bowl, a downward suction is created. If the water level within the tank is too low, there won't be enough suction in the bowl and it'll cause the toilet to flush slowly.

Check the water level in your tank. It should be about 1/2" below the overflow pipe. If the water is lower than 1/2", then this is your problem. 

The Fix

There are several reasons your toilet tank is not filling to the proper level. A common problem is the fill valve is not properly adjusted. The fill valve uses a float to indicate when to shut off the water flowing into the tank.

By adjusting the float, you'll be able to increase the amount of water in the tank. Learn more about fill valves here.

Another cause could be due to low water pressure, if this is your problem you may want to call a plumber to troubleshoot and determine the best course of action.


When the toilet is flushed the waste water travels down a drain, through pipes, and eventually into the sewer or septic system. If there's an obstruction along this path, then your toilet will not be able to efficiently flush. A partial clog can cause your toilet to flush slowly and could eventually lead to a major headache.

The Fix

First try to dislodge the obstruction with a plunger. Plunge vigorously 20 times, up and down, this will hopefully create enough pressure to remove the clog. 

If this doesn't work, you should call a plumber or a service such as Roto-Rooter.

Most toilet clogs are due to flushing things that should not be flushed down the toilet. However, if you are on a septic tank system, the problem could be more serious, as tree roots may be causing the obstruction. This is definitely a job for a professional.


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Toilet Flapper 

Another issue could be a worn or faulty flapper valve. When the handle on the toilet is pressed, a rubber flap is lifted from the bottom of the toilet tank, and the water in the tank is released into the toilet bowl. 

The act of pressing the toilet handle is what lifts the flapper.

The flappers are made of rubber and over time they simply wear out and are no longer to create the seal that prevents the water from entering the toilet bowl. This will allow the water to slowly leak from the tank and weaken the toilet's flush.

In most cases, you'll notice the "running" sound of water coming from your toilet.

The Fix

Although you can call a plumber to make this fix for you, it's relatively easy and inexpensive to replace the flapper. The part itself is typically less than ten dollars and all you need to do is replace the old flapper with a new one and adjust the chain length. 

Although it is possible you'll need to replace the entire flush valve, this job is also relatively easy and inexpensive.

Mineral Build-up

When the toilet is flushed, the water from the tank enters the toilet bowl through small jet holes which are located under the toilet's rim. The location of the jet holes can often mean they're missed when the toilet is cleaned.

Over time, especially in areas with hard water, the jet holes can develop a mineral build-up and block the flow of water into the bowl. If your toilet isn't clogged, but it is slow, then it's very possible that this is the problem

The Fix

the jet holes can be easily cleaned with a stiff bristled toilet brush and white vinegar.  

Spray the white vinegar under the toilet's rim and allow it to soak for 30-minutes. Then scrub the area with your toilet brush. Repeat if needed.


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