a man is fixing the toilet

How to Fix a Weak Flushing Toilet

A toilet can still flush even if water enters the bowl reasonably slowly. But, it’s best for the toilet to flush normally, as this will make it less likely for a toilet to clog. So, here’s what to do if you have a weak flushing toilet.

As a general rule, there is something blocking the exit pipe, the water tank is not filling all the way, or the pipe from the water tank to the bowl is slightly clogged. Use a plunger to clear the exit pipe, inspect the water tank, and pipe from the water tank to the bowl.

Below, I will explain these troubleshooting steps in more detail, and why they cause a toilet to not flush with a good amount of force to completely clear the bowl.

Step by Step How To Fix a Weak Flushing Toilet

There are two forces that cause a toilet to flush properly, the suction force of the water as it makes its way over the kink in the exit pipe and the force of the water entering the bowl. Therefore, if there’s an issue with it not flushing strong enough it’s due to an issue in one of these places.

To understand why this is the case, here’s a really good video from a plumber that explains how a toilet works:

The main reasons are:

  • The water tank doesn’t fill completely 
  • The water tank does not completely empty
  • There is a blockage in the exit pipe
  • The holes where water enters the bowl and clogged

A blockage in the exit pipe creating a poor suction

The most common reason is that there’s a blockage in the exit pipe. This causes only a small amount of water to move through the exit pipe at a time. This needs to be cleared with a plunger.

person using toilet plunger to clear the blockage

Also, if you flush a toilet multiple times, it can clear the blockage. This is most often seen when water pools inside the bowl rather than completely emptying. If you don’t have a plunger on hand, wait until most of the water empties, and then try flushing it again. This typically can take an hour or so. 

The reason is there’s a blockage, and the water trickles through the exit pipe and doesn’t empty completely. With a few flushes, it can clear the exit pipe enough that the water can create a good enough suction to pull through the remaining blockage.

If you do this multiple times and it still doesn’t clear the blockage then get a plunger. A plunger works by creating a seal in the pipe. Then you press down on it, and it pushes the blockage through. Also, when you push it up and down it pushes and pulls the blockage, making it looser. And causing it to be loose enough for the water pressure to push it through.

Water tank not emptying completely – weak downward force

The other force that makes a toilet flush properly is the water exiting the water tank. A water tank has a pipe that is quite wide and allows water to flow through at a very fast rate. 

toilet tank with water in it

The force of the water exiting the water tank is enough to push the waste over the kink in the exit pipe. But, if not enough water exits the water tank it will cause a weak flush.

There are also different types of toilets. These are:

  • Toilets that completely empty the water tank with one press of the button
  • Toilets that require you to hold the button down for 2.5 seconds

It’s possible you’re not holding down the button long enough to completely empty the water tank. Therefore, it’s not generating enough downward force with the water to push the waste over the kink in the exit pipe.

The holes where the water enters the bowl are blocked

Water enters the bowl through an opening near the top of the bowl. These can become dirty and filled with grime. Or, hard water deposits can accumulate and partially block them, according to plumbing experts. This makes it take longer for the water tank to empty. Or the water tank may not empty completely when you flush it.

To identify if this is the issue refer to this article about how to clear a blocked toilet. It explains how to test if this is what is causing a weak flush.

a flushing toilet

How Can I Get My Toilet To Flush Stronger

A weak flushing toilet means it can often take a few flushes to empty the bowl. There are 3 causes of a toilet not flushing strongly enough. So, here’s how to get your toilet to flush stronger.

In general, there is a blockage in the exit pipe, the water tank is not full, or the water tank is not completely emptying. Clear a blockage using a plunger, and inspect the water tank to make sure it’s filling up all the way, and that it empties completely.

If the water tank is not filling all the way, there is an issue with the buoy mechanism. This is inside the water tank. As the water tank fills up the buoy rises until it seals off the water inlet valve. It can require a plumber to fix, but there are a range of good troubleshooting videos on Youtube which will show repairs that can be done yourself.

There may also be something stuck in the water outlet valve between the water tank and the bowl. This will cause the water to flow into the bowl more slowly.

Why It Takes Two Flush to Flush a Toilet

A toilet that is working properly will only take one flush to completely empty the bowl. If a toilet has an issue it will take two or more flushes, and water can pool inside the bowl. Here’s what to do if your toilet takes more than one flush to empty completely.

Overall, it’s because there’s a minor blockage in the exit pipe at the base of the toilet, the water tank is not emptying completely when you flush it, the water tank is not filling up all the way in between flushes, and/or the holes where water enters the bowl are slightly clogged.

It’s necessary to inspect each of these to identify what’s causing the issue. A blockage can be cleared using a plunger. If a plunger doesn’t work, then you should use a plumbers snake.

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