5 Reasons Your Toilet Keeps Clogging

Discover the reasons for constant toilet clogs and learn how you can fix them.

person using a plunger on a clogged toilet

The Spruce / Letícia Almeida

In modern society, a toilet isn't just a convenience, it's a necessity to have in a home. When the toilet is experiencing problems, it's important to figure out exactly what is causing the issue and repair it as quickly as possible. Clogged toilets are usually blamed on a child or overzealous adult that puts a bit too much toilet paper into the toilet bowl before flushing. These issues can typically be fixed by plunging the toilet bowl, but when a toilet regularly clogs, even with an acceptable amount of toilet paper and waste, then there may be a bigger problem to solve.

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Flushing Wipes, Paper Towel, and Other Non-Flushable Items

It's a common misconception that certain products can be flushed down the toilet without any problems. For example, wipes, even products that are marketed as flushable wipes, actually cause a significant amount of problems to the home plumbing system, and they are even a severe issue in the larger municipal sewage system. Paper towels are another product that seem like they should be flushable, but most paper towel products are made to resist tearing, even when they are completely saturated. This physical resistance makes them difficult to break down and pass through the drain pipe.

Disposable cloths, feminine products, napkins, ear swabs, and hair are also common items that people try to flush down the toilet, but it's important to understand that the toilet isn't a garbage can. It is not designed to work with these substances and flushing them can often lead to clogs in the toilet or further down the line, which can create ongoing issues for the entire plumbing system.

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A Partially-Blocked S-Trap

If you look at the back of the toilet, there is usually an S-shaped pipe that comes up from the ground and winds its way into the toilet bowl. This pipe is known as an S-trap drain, and it is responsible for ensuring that the odorous sewer gases in the drain pipes cannot pass through the toilet bowl and into the home. Due to the difference in toilet design, the pipe isn't always visible, and in some cases, the toilet uses a P-trap instead of an S-trap, but the purpose remains the same.

A fully clogged S-trap or P-trap is easy to identify because the toilet clogs and needs to be cleared before it can be used again, but if the S-trap or P-trap is partially blocked, then the problem may not become apparent until the toilet fully clogs. Partial blockages can remain in place even after the main clog is cleared, causing the toilet to clog more frequently than normal. Consider using a toilet auger to pull out or break up the partial clog and move it through the drain. If this doesn't work, then you may need to call a plumber to clear the blockage.

Obstructed Plumbing Vents

It's surprisingly uncommon knowledge that the plumbing system in a home doesn't just consist of water pipes to bring water to the various outlets and drainpipes to remove the wastewater from the home. The plumbing system also relies on ventilation pipes that make it possible to release sewer gases safely through the roof of the home, instead of having the pressure build up within the drainpipes. These lines also allow clean air from outside to enter the system, creating suction and pressure within the line, which increases the flushing power of the toilet.

However, if the plumbing vent is sealed, clogged, or otherwise obstructed, then the flushing power of the toilet is greatly reduced. To verify if this is the problem, one person will need to stay with the toilet, while a second person climbs up onto the roof to access the plumbing vent. A third person should always be holding the ladder and spotting the individual on the roof.

Have the first person flush the toilet while the individual on the roof holds their hand over the vent. If there is no suction from the vent, then it is blocked and will need to be cleared with a plumber's snake. Alternately, the vent could be blocked at the outlet and simply needs to be cleaned by hand to resolve the situation.

Punctured, Damaged, or Restricted Main Sewer Lines

The main sewer line that exits the home runs underground and out to a municipal sewer system or it may run to a septic tank. Due to its position under the ground, the sewer line is relatively well-protected from rain, sleet, snow, and freezing, however, it is vulnerable to tree roots, which can wrap around the pipe or puncture the pipe. If the main sewer line is punctured or compressed, the outlet to the septic tank or municipal sewer system is constricted. Additionally, rocks, dirt, and other debris can enter the line through the punctures, creating further drainage problems. Keep in mind that if this is the case, then more than one toilet or drain should be experiencing issues. Call a plumber to address this problem and be prepared to have the main sewer line dug up and replaced.

Ineffective Low-Flow Toilet

Low-flow toilets are excellent options that help to reduce unnecessary water usage and also lower the water bill. However, toilets can last for more than a decade before needing to be updated or replaced, and outdated low-flow toilets can cause clogging issues because the power of the flush is not substantial for pushing the toilet paper and waste completely through the S-trap or P-trap and into the drainpipe. This issue can be mitigated by flushing a small amount of toilet paper and waste at a time, but it's better to simply upgrade to a new low-flow toilet that can handle the demands.