Why Is My Toilet Overflowing

An overflowing toilet refers to when water and waste, instead of flowing down the drain, either back up or remain in the bowl.

If the overflow is stagnant and not spewing wastes unto your bathroom floor, you’re in luck since you have many options at fixing this.

The causes of an overflowing toilet include a clog in either the toilet bowl, drain pipe, toilet trap, or lateral sanitary sewer line.

It can also be due to a low flow toilet, a poorly working septic system, or improper plumbing. The solution is stopping the water flow, dealing with the case, then cleaning up afterward.

Always, the first thing you need to do is stopping the overflow before anything else. It’s the difference between a mild overflow and a house filled with wastes.

What Causes A Toilet To Overflow?

Simply put, a toilet overflows because it’s either clogged or not working properly.

The problem can be anywhere from the toilet bowl all the way to the septic tank. Some causes can be easily diagnosed at home while others will need the skills of an expert to pinpoint.

The most likely causes behind an overflowing toilet include the following:


Clogged toilet bowls are among the most common causes of overflowing toilets. The reason for this is that a lot of the items flushed down the drain are either not meant to be flushed, or are not in a flushable state.

Only soft and water-soluble materials should be flushed down the drain yet people flush diapers, handkerchieves and many other items. These only end up blocking the narrow bowl exit to the drain.


anatomy of a toilet drain

The drain pipes are the ones linking your toilet in the house to the sewer line outdoors. They’re the only vertical ones going downwards to the lateral sewer line.

These pipes often have various bends and joints which can lead to clogging whenever something large is flushed through them.


The p-trap is the p-shaped section just below the toilet bowl which holds water and keeps sewer gases from entering your home. Often, items get stuck in this section of the toilet owing to the many corners they have to make before getting to the drain pipes.

At times, the trap could be calcified such that it starts catching toilet paper when flushed.


The lateral sanitary sewer line connects the vertical drain pipe to the main sewer outdoors. This pipe is likely to be clogged with solid items such as diapers given that the water pressure in it is relatively lower than in the rest of the drainage system. Roots can also grow into them causing blockages.

A clog here and in the drain pipe may take a while to have an overflow in the house but will eventually get there.


increase water level

Low flow toilets are meant to conserve water by allowing only a certain amount of water to be used at each flushing.

While this is an advantage in terms of conserving water, it may lead to a less-than-optimal flushing. The toilet may not release enough water to flush down all the dirt.

This may lead to clogging and it’s eventual overflowing.


At times, the overflowing toilet may be due to a full septic tank.

When wastes have filled up the septic tank, it can back up to the toilet bowl. Other times, the septic tank may be filled with water from rain or a burst water pipe.


plumbing system malfunctioning

Any part of the plumbing system can malfunction leading to an overflowing toilet. For example, the flushing handle may get stuck or the floater may not work properly leading to an endless flow of water.

For this case, the overflowing will often occur in the cistern rather than the bowl of the toilet.


The vent stack is the pipe sticking out of your roof from the toilet. While it’s meant to keep the foul smell from your toilet away from the house, it also balances the air pressure for the whole drainage system.

If it’s blocked by leaves, rodents or other objects, it’ll not work properly. Instead of flowing downwards, the waste water can be sucked upwards and into your toilet.

Any of these issues may lead to your toilet overflowing. While some like a blocked toilet bowl are easy to identify and resolve, others such as a dysfunctional sewer system may require an expert to address.

How To Stop An Overflowing Toilet

As scary as it may sound, an overflowing toilet can be handled with ease. In the sections below, you’ll find solutions to this issue and what to do to avoid making the issue worse.


first stop the water

The first thing to do is stopping the water to bring the issue under control. The overflow is a sign that there’s too much water that’s not flowing in the toilet system. Flushing the toilet in more panic will only worsen the issue.

What you need to do is avoid flushing the toilet and even shut off the water supply either from the shut-off valve or the main tank supplying water to your toilet. Given that the toilet often shares the drainage with other outlets such as the sinks and bathroom, shut off the water supply from these places as well.

After that, the focus should be identifying the location of the clog (or other issue) and fixing it.


man fixing toilet valve

The method you employ in unclogging your toilet depends on the location of the clog and the nature of the toilet overflow. The most common methods of unclogging a toilet include the following:

  • Toilet plunger: This requires plunging the toilet bowl as many times as it takes to force the clog down the drain. It’s among the most effective unclogging procedures since it forces water and air into and out of the drainage system. This easily dislodges the clog.
  • Toilet auger: The toilet auger is perhaps the best when it comes to unclogging an overflowing toilet. This is because it doesn’t disturb the water but seeks out the clog and breaks it down to allow the water to flow freely.
  • Hot water: if the toilet isn’t spewing dirty water into your bathroom, pouring a gallon of hot (not boiling) water down the drain and using the plunger to force it into the system helps unclog the toilet.
  • Bleach and dish detergent: Pouring 3 cups of bleach and 1 cup of dish detergent into the toilet bowl and waiting for 30 minutes can ease the clog in the piping system.
  • Epsom salts: Epsom salts can be used to soften the clog and thus flush it away. If you don’t have a pack of Epsom salts, use a bath bomb or other item that has lots of them. Simply put them into the toilet bowl and plunge it after an hour.
  • Shampoo or dish soap: The slippery nature of shampoo and dish soap makes it possible to lubricate a blockage down the drain. Simply add 3 cups of dish soap or shampoo to the toilet bowl then wait for 30 minutes before plunging it.
  • Cloth Wire Hanger: A cloth wire hanger makes a good toilet auger. You have to untwist it then use the end without the hook to push down the blockage in the toilet bowl and the p-trap. Given its short length, you’ll only use it when the blockage is either in the bowl or the p-trap.
  • Baking soda and white vinegar: A cup of baking soda mixed with 2 cups of white vinegar can unclog a toilet owing to the way they react to one another. This reaction is able to break down the clog and stop the overflowing of the toilet.
  • Clear the vent stack: If the issue is a blocked vent stack, you’ll need to climb to the roof and push a long stiff wire or other object to clear the vent stack for proper air pressure balance in your toilet.
  • Fix the floater mechanism: For cases of an overflowing toilet cistern, fix the floater such that only the needed water level is availed in the cistern. This may require loosening the floater screw such that the floater lets in less water than before.

If you’re not able to stop the overflowing by yourself, call for an expert who will deal with it in no time.


clean up dirty water

When the overflowing has been stopped, you then start cleaning up all areas affected by the dirty water. You have the option of using rugs or a wet-dry vacuum cleaner to dry up the floor as soon as possible.

The aim is to prevent the contamination of the house and water damage to the floor, walls, cabinets and even the ceiling if the toilet is upstairs. Use strong detergents since chances are high that the overflowing water is contaminated even when it’s clear in color.

You should clean up and dry the surfaces as soon as possible to prevent the growth of bacteria and other harmful microorganisms. Use fans or hot air blowers to dry out the affected areas fast.

After the cleaning process, sanitize all the affected surfaces to completely do away with the germs.

At times, you may have to replace some parts of the house after the toilet has overflowed. These include cabinets, walls, doors, ceiling parts and others as you’ll deem appropriate.

Also, ensure that the overflowing water didn’t affect the electric connections of the house. This is usually the case when the toilet overflowing is upstairs. If you’re not sure about this, simply turn off the power and wait for an expert to fix it.

Lastly, always protect yourself when cleaning up the affected surfaces. Use rubber gloves, a ventilator, rubber boots and protective clothing such as an apron when cleaning. Cover your eyes as well with clear goggles to prevent dirty water from splashing into them.

If you’re not able to clean the house properly, leave it to an expert as they have experience with similar cases and will thus provide the best cleaning solutions.

How To Prevent A Toilet From Overflowing

The surest way to keep your toilet from overflowing is to only flush objects that are meant to go down the drain. That’s basically soft tissues that dissociate when they come into contact with the water.

Solid objects, however small, can cause a blockage in part of the drainage system given its narrowness and the many bends typical with such systems.

Avoid flushing diapers or toys and other solid items in your toilet. Even with toilet paper, using a reasonable amount will keep your toilet clog-free. With kids the most likely culprits of toilet blockages, teaching them these lessons will save you a lot of headache.

If your toilet frequently clogs in normal use scenarios, consider changing to a 1 ply toilet paper roll. You can also enlist the services of a plumber to carry out routine checks on the whole system to prevent the occurrence of such issues.