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Toilet Flushes But Waste Comes Back: Here’s Why and How to Fix?

We all want to use clean toilets. You don’t want the waste to come back even after you flush the toilet. However, it’s a rather typical issue in every home, and we will assist you in fixing it right away.

So why does the toilet flush but waste comes back? There could be multiple reasons behind the waste coming back even after flushing. The most common reasons behind it are; a clogged toilet, a faulty flapper valve, and a malfunctioning plumbing vent.

However, when it comes to fixing them, it’s not that difficult and you can do it yourself. So that’s what we are going to do today, assist you in fixing it on your own by providing a step-by-step guide. Let’s take a look at the symptoms first so that you can identify the problem first.

Table: Toilet Flushes But Waste Comes Back [Problems and Symptoms]

Before we jump into details, here is a table of problems and symptoms.

Clogged ToiletSlow drainage
Emit foul odors
High water level in the toilet bowl
Faulty Flapper ValveWater Leak into the bowl continuously
Flushes the toilet on its own
Emit foul odors
Malfunctioning Plumbing VentWater backs up into other fixtures such as sinks
Gurgling sounds coming from the drain

Toilet Flushes But Waste Comes Back: Causes and Solutions

As already mentioned, there are three reasons why you might come across a faulty toilet flush. Let’s go in-depth with the problems and then provide you with a fix for them. 

1. Clogged Toilet

A clogged toilet that makes the waste come back to where it was is called the toilet backflow. This prevents waste and water from exiting the toilet bowl and moving freely through the pipes. As a result, when you flush the toilet, the water and waste may go back up instead of going down.

Nevertheless, there are several causes for clogged toilets. Flushing non-biodegradable goods like paper towels or baby wipes is one common cause. These objects tend to become jammed in the pipes, obstructing the flow of waste and water.

On the other hand, flushing too much toilet paper can also lead to clogging. Even though toilets are meant to flush toilet paper, an excessive amount is just something it can’t process.

How To Solve It?

To solve the clogging, we will go through the default plunger method. Here, all you need is a plunger to fix the issue. The step-by-step guide is provided below;

Step 1: Wear gloves and cover the area around the toilet with newspapers so no waste water comes in contact with the washroom.

Step 2: Grab a plunger that fits into the toilet drain opening.

Step 3: To create suction, position the plunger over the drain opening and gently press down. Then, immediately pull up to generate a vacuum that will remove the clog.

Step 4: Repeat this process multiple times and check to see if the water is draining at regular intervals.

Step 5: Flush the toilet.

solve the clogged toilet issues

2. Faulty Flapper Valve

A rubber seal at the base of the toilet tank is called a flapper valve. It controls the amount of water that flushes from the tank into the toilet bowl. The problem begins when the valve doesn’t create a strong enough seal. As a result, the water pressure is not strong enough to get rid of the waste.

The reason behind a faulty flapper valve is mostly due to using it for a long period. Due to exposure to chemicals in the water, such as chlorine, the rubber material of the flapper may eventually deteriorate or split.

However, it’s also possible for an improper installation to damage the flappy valve. Thus, the installation part must be done properly to not come across problems like this frequently.

How To Solve It?

You need to replace the flapper valve to fix this issue. Here’s how to replace it;

Step 1: Turn off the water supply.

Step 2: Empty the toilet tank by flushing it multiple times.

Step 3: Open the toilet lid.

Step 4: Disconnect the flapper valve from the chain, then slide it off the pegs holding it in place.

Step 5: Take the brand new flapper valve and slide it in the pegs to connect it with the chain.

Step 6: Turn on the water supply and wait for the tank to fill before use.

Here’s a video of replacing the flapper valve that will help in visual guidance;

3. Malfunctioning Plumbing Vent

When a toilet is flushed, wastewater travels through the pipes and is vented outside the building. Its main purpose is to give the plumbing system ventilation so that air may enter and leave the pipes when wastewater is pumped through them.

Consequently, a vacuum is created in the pipes when the plumbing vents are not operating effectively due to a lack of ventilation. The flow of wastewater gets slowed or stopped as a result.

And being unable to leave the house properly, wastewater may begin to back up into the pipes and eventually reach the toilet.

How To Solve It?

Get up to the roof of your house to fix a broken plumbing vent. You’ll need a hose and access to a water source on the roof.  Once you are prepared, you can follow the guide provided below;

Step 1: The plumbing vent can be located as a narrow pipe sticking out of the roof.

Step 2: Inspect for any visible and accessible blockage in the vent.

Step 3: Clear any blockages using anything that you might find handy.

Step 4: Use the hose to pump water down and clean any obstructions that are difficult to reach.

You need to call a professional plumber as the blockage might be significant If it’s still not solving the issue.


Let’s check out some frequently asked questions regarding this issue.

Q: How can I prevent waste from coming back after flushing the toilet?

The first step is to stop flushing non-flushable items like baby wipes into the toilet. Secondly, doing a regular checkup on the plumbing system can keep the system in the best condition.

Q: Why does my toilet gurgle when I flush it?

Toilet gurgling is a clear sign of clogging. You need to immediately take a plunger and do some plunging to free up the toilet.

Q: Why does my toilet smell bad even after flushing?

It’s a sign that not enough water is flowing through during flushing. The most possible reason for this is a faulty flapper valve. However, a clogged toilet can also be the reason.


To conclude, there’s nothing to worry about when the toilet flushes but waste comes back. It’s quite a common problem and can be fixed easily by yourself. You just need to make sure the toilet is not clogged, the flapper valve is working and the plumbing vent is not obstructed. However, things can get out of hand and that’s when you need to call a professional to take charge. They have access to specialized tools and experience that will solve it in an hour.