Why is my Toilet Overflowing But Not Clogged(4 solutions)

An overflowing toilet is a big mess and happens for several reasons. Finding the central source of an overflowing toilet is also a tough job.

Because whenever a running toilet not only ruin the bathroom even spread diseases.

Today you are here, (obviously)you search a lot, there are so many options, causes make you doubtful and more frustrated.

That’s why I’m not going to mislead you around and put only the exact possible reasons for a toilet overflowing but not clogged.

You’ll get the solution about why your toilet keeps overflowing, not blocked, and how to fix an overflowing toilet that isn’t clogged.

Why is my toilet overflowing but not clogged?

Whenever you see your toilet is running- you may ask yourself, “why is my toilet overflowing but not clogged?

For the straight answer, a toilet is running may different reasons like a torn flapper, after changing the new flapper, toilet tank malfunction, blockage pipe, Worn out gasket, etc. 

But in case there is no blockage, then for sure the issue with Vent pipe, Septic tank or the Siphon Jet.

Why is your toilet overflowing but not blocked- Due to the VENT PIPE 

Vent pipe or AAV pipe may be the potential reason to overflow a toilet for no reason, what happened with my Kohler Tresham a while ago.

The vent pipes are also referred to as plumbing air vents or vent stacks. The vent pipe directly goes to the rooftop. It maintains the air outlet-inlet and the air pressure.

Do you know almost 80 to 100 gallons of water use in the household in America each day? You won’t believe the maximum of the water just waste down via flush.

Here the vent pipe plays a significant role to controls circulation to ensure that waste and water dump out of your home over drainage pipes.

The vent system hinders a vacuum from forming, resulting in sluggish or no drain. It always keeps the drainage system clear and flowless.

Because a plugged vent will not allow air to circulate across and enter the pipes, the wastewater will continue to rot in the sewage system. 

However, the excess wastewater builds up in the passages at the one point where the pipe can’t stock longer- This might cause water to flow right back and out of toilets.

How do I know if my vent stack is clogged?

Blocked or Faulty Plumbing vent pipe is one of the causes for an overflowing toilet. 

The very first thing to check after ensuring that there is no clogged till the toilet is overflowing is the vent pipe.

But how to know the problem with the vent pipe? Yes, you can by following the steps.

Noise. Yes. If the vent pipe is the problem, you may notice a weird sound come from the toilet like 

  • gurgling, 
  • Sewage smell
  • Filthy water remain 
  • The running water is dirty enough to kill your nostrils.
  • Sluggish drains
  • Very slow flush

Do you have any of those signs? If so. You have to fix the rooftop plumbing vent pipe.

The second most reason for an overflowing toilet that is not clogged anywhere is- A FAULTY SEPTIC TANK

Around 20 percent of Americans count on a septic tank. Most other use municipality systems.

If you have your own Septic tank, then you know about the capacity of the waste materials. 

Septic tanks keep the home by collecting all human debris. Thus, it is necessary to clean the septic tank after a certain period of time or inspect the level of waste products deposited in the septic tank. 

However, if a network is unattained, it might generate a number of issues, including overflowing the toilet with poop and the pot not getting flushed.

Such things will not only cause inconvenience in daily lifestyle. But can also result in costly maintenance and, in some circumstances, health hazards.

How do you know if the septic tank is full/ How do you determine the running toilet due to the Septic tank?

  1. If the septic tank is full- the number one indication is the toilet back up.
  2. Dung smell all over the house, lown.
  3. The filthy water seeping around the septic tank from the ground, and the area gets soggy by the wastewater.
  4. Water drain very slow all faucets like tub, sinks, toilet, etc.
  5. While your septic tank is overloaded, your toilet will appear weirdly. When you flush may notice that it doesn’t entirely flush or flushes extremely slowly over time but is not blocked.
  6. Strange noises crop up.

Do you notice any of these signs? If yes, then you have to clean or pump the septic tank.

The last cause no clogged overflowing toilet is – THE TOILET TANK MALFUNCTION 

The toilet tank is a very sensitive part of any toilet. The tank always controls the flushing mechanism. 

The toilet tank has many small and large parts that help hold all the water, like the Flapper, Gasket, Ballcock.

The Flapper- If the flapper gets too old, mineral deposition may cause the flapper to either not close or wear out.

In fact, a wrong size flapper also may cause running water. 

Now, you may question how do you know the flapper has the issue? Right.

To check the water quality. Water from the malfunctioning tank is always clear and has no smell. Besides that, you may hear a Hiss sound come from the pot. 

While you flush the water, drain properly, but water is running continuously from the leakage flapper.

The Gasket – Gasket is present between the tank and bowl beneath the flapper seal. The gasket is a rubber seal that prevents water leakage while flushing.

If your toilet is overflowing while flush and the water leak from between the toilet tank and bowl- then the Gasket seal has the problem.

To solve the issue change the gasket seal. 

How To Change The Gasket Seal

To change the Gasket Seal, take one towel, bucket, etc.

  1. Turn off the water line that connects to the tank.
  2. Flush down the entire water from the tank and remove the excess water by using a towel or tissue.
  3. Unscrew the main water line.
  4. Lift the tank from the bowl.
  5. Remove the old gasket and place the new one.
  6. Place the tank its place again, connect the waterline.
  7. Allow the water to fill the tank and flush once for a check.

How Do I Fix an Overflowing Toilet That Isn’t Clogged?

At first, turn off all water supplies that connect to the toilet. All the above inspections, check out which is the main cause and work on that.

How to Fix Plumbing Vent Pipe that causing toilet overflow without clog?

Fixing a vent pipe is easy. You can do it yourself or hire a professional for that.

Climb the rooftop carefully with a flush light. Check any object present or not. Take a garden hose and spray over the vent pipe.

The water pressure can clear the system. You can use a toilet snake and snake it out if any object is stuck there.

After all, have done by your side till the problem is present, call a professional. Don’t put yourself in danger.

  • To keep further blockage, use a Vent Cap (From Amazon)It is reliable and prevents any bird, leaves from being stuck down the plumbing pipe.
  • Upgrade or replace the vent stack if it gets too old or bent somewhere.

How to Fix Septic Tank Problem which creates a toilet for overflowing

If you have your own septic tank, it is necessary to keep maintenance after 10 to 12 years alternative periods.

You can’t do with the septic tank. Septic tank clearance is a professional job, so don’t waste time. Call your nearest plumbing station and discuss the problem you have.

They know the best and solve your issue.

Bottom Line- The toilet is overflowing, and It’s Not Clogged 

As you understand, to observe your situation and facts, never avoid an overflowing toilet.

One toilet never overflowing within a night, the problem arise a long time ago, and suddenly you see the mess. 

When a toilet is about to overflow, there are warning signs to come from the toilet. You should heed the warnings.

Such as-

Like those signs want to you tell about the future mess.


Q1. Can a Bad Flapper Cause a Toilet to Overflow?

Yes. A defective flapper is periodically causing a toilet to run, leaking even overflow.

Q2. How to Sanitize After Toilet Overflows?

It is a very important part to sanitize all the bathroom space after fixing the overflowing toilet because filthy water spread germs very first.
1. Mop up all water and dry out the bathroom.
2. Use bleach. Take a one to a quarter cup of bleach add into one gallon of water.
3. Wipe down with the solution all over the places where the wastewater is reached.
4. If you have a bleach allergy, you can use the toilet disinfectant (From Amazon)  and sanitize the area. Don’t forget to wear gloves.
Or call the plumbing department to clean.

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