When we see a toilet is flooding insanely, it becomes like a fainting situation, and if the toilet is not flush same time, then it is over.

Do you have the experienced same, like me? Then you have landed on the right page. In the next 2 minutes, you will get to know the reason- why your toilet is flooding and not flushing.

Although flooding the toilet due to the vent pipe issue, sewage issue, septic system, and internal clogging, flushing due to clogging again, drain pipe error. 

Lets’ find out what’s yours.

Why Is My Toilet Flooding and Not Flushing

There is Four primary cause for a toilet not flushing and flooding at the same time.

All are very significantly affected during the flush, and unless you’re working on that problem, your toilet will become messier.

Issue No.1- Blocked Vent Stack or Plumbing Vent

A plumbing vent is a vertically placed system all over the fixture, which allows the air to pass through it. 

All types of sewage air pass through the plumbing vent and are released outside the house. 

The vent stack has neutral air pressure than the surrounding atmosphere. It helps to air goes upward direction and block going back to faucets and toilets.

Also, help the solid and liquid object goes down directly to the sewage drain.

But in this case, if the toilet is overflowing or flooded, it means the air that should go outside comes back, and the water should not go down due to the air pressure. As a result, flooding and not flushing.

All because the plumbing vent is blocked somehow, and make this mess. But the best part is you can identify whether it causes by a clogged vent or not.

Trick1. The sound. Yes. If our vent pipe is the source of the problem, your toilet will make a gurgling or bubbling noise.

Trick2. After sound, place one hand over the water supply pipe- you can feel the vibration within the pipe.

The accumulated air creates vibration and noise. I have a detailed post about blocked vent pipe indications. If you want, check this out.

Is the culprit your vent pipe? If, so go unclog it. Either hire one expert, or you can do it by yourself. I’ve detailed two articles on that too. 

What are you prefer! Climbing on the rooftop (check here) or unplugging the vent stack without going on the roof are both possible options.

Issue No.2- Internal Clogging of The Toilet

Toilet clogging is another reason for a toilet not to flush and flood, like a lunatic. 

Do you know that more than 80% of American homeowners experience clogged drains at least once every one-week interval?

Clogged toilets because of toilet papers, toys, hair, foreign object, other solid not dissolve items either accidentally flush down or naughty babies do it.

 Read More- What to do if any unknown object is stuck inside the toilet trap way? 100% work, proven methods

Or, due to the long age of drain outlet of toilet has a mineral deposit in the drain becomes narrow and does not flush.

The S-shaped pipe or trap way right behind your toilet is responsible for keeping away sewage gas entering back to drainage more prone to clog.

But how do you know, clogging may be the cause? Right? The smell and the water condition.

Trick1. If your toilet drain is clogged, no sewer smell comes out, the water is clear

Trick2. The toilet is flooding but flushing very slow.

Fix– If you feel the drainage pipe is a plug, use a toilet snake or auger to clear the pathway (Check Here).

Issue No.3- Septic Tank Is Full

Do you have your own septic tank instead of a municipal sewer system? If so, how long time it’s been clear? The Septic tank must clear every 8 to 10 years.

Flood toilet and not flush one of the indications of septic tank is full. 

Septic tanks hold waste and discharge excessive fluid into the drain field- which is the soil mostly around the chamber.

But, full of waste and water, septic tanks fail to discharge the water around the soil and return back to your toilet. -this causes toilet flooding and not flushing.

But how do you know, a septic tank may be the culprit? Right? The smell and the water condition.

Trick1. Observe watercolor if it is totally disgusting, unbearable smell, and black in color- it’s definitely the septic tank.

Trick2. Sometimes water contains waste also.

Fix- Call immediately one expert to clear the septic tank. Otherwise, it becomes messier; even you can’t imagine that.

Issue No.4- Sewage Issue- Toilet Overflowing with Poop

The main pipe runs through under the ground and joins the central town or municipal sewer channel.

But in the way of a sewer pipe, tree root or plastic materials may block the passage. Over time, soil, solid, and undegradable objects accumulate and create a plug.

Many commercial items state that it dissolves after sometimes which actually not or these sometimes become a long time, in between plug generates.

Now, the main sewage unable to pass the waste can induce a flooded basement or an overflowing toilet.

If the sewage can’t drain properly, it will return up your line. It’ll get into your house through the lowest point, which is normally the basement toilet.

But how do you know, a sewage issue may be the culprit? Right? 

Trick1. The most affected toilet is the basement one.

Trick2. Observe watercolor if it is totally disgusting, unbearable smell, and black in color.

Trick3. Whether you shut off you’re mainline of the house, still flooding.


Trick4. Ask your neighbor. I guess they also suffer the same.

Fix- Don’t waste a single second, call the nearest or local sewer department, tell them the whole situation.

Issue No.5- Other Secondary Causes for Your Toilet to Flood and Not Flush

The major and primary issues are above, below are the secondary causes, including

  1. If there is a natural disaster, flood in your area. If you live in a flood area, the toilet can’t flush and overflowing
  2. A slow septic tank system
  3. Old pipe system
  4. Blockage somewhere else in your plumbing system
  5. Breakage any sewer line

Final Thought- Why is My Toilet Flooding and Not Flushing

Flooding toilet is a big concern issue, one single step can make it more and more worst. Without knowing the cause may damage the property.

Not only about property, overflowing toilets bring all the nasty water and sewer smell into your house, that also unhealthy.

Sewer water can cause harmful bacteria to thrive that are again life-threatening.

While you have to face this situation, call your nearest plumbing service- they immediately reach your place and solve the problem.

FAQs- Won’t Flushing with Flooding Toilet

Q1. Can a Toilet Flood a House?

Yes. An overflowing toilet can flood all over the house, cause property damage, health issue, Finance issue, etc.