5 Reasons Your Toilet Keeps Clogging

Causes and Fixes for Toilets That Clog Repeatedly

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.

Toilets can develop drain clogs for any one of several basic reasons, usually involving partial or complete obstruction in one of the various parts of the drain system: the toilet trap, the branch drain line, the vent pipe, or the main sewer line. Most commonly, the remedy for a clogged toilet is to simply to plunge the toilet bowl, but when a toilet clogs repeatedly, even with an acceptably small amount of toilet paper and waste, then there may be a bigger problem to solve.


Click Play to Learn How to Fix a Clogged Toilet

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, menstrual 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.

How to Fix It

Clogs caused by foreign materials can usually be cleared by forcing the clog through to the main sewer line by plunging with a toilet plunger, or by extracting or breaking up the clog with a toilet auger (snake). But unless your family develops good practices, such clogs are likely to recur.

Strongly coach all family members to be diligent about flushing only biodegradable materials down the toilet. Provide wastebaskets in each bathroom to provide a place to dispose of incompatible items.

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A Partially-Blocked Toilet Trap

Inside the porcelain base of the toilet, the toilet outlet enters a curved channel that is designed to hold standing water and prevent odorous sewer gases from passing through the toilet bowl into the home. This is the feature that keeps a small amount of standing water remaining in the bowl after each flush. This S- or P-shaped section of the porcelain bowl is what connects the toilet to the home's drain pipes. In most cases, you can identify the built-in trap of the toilet base when looking at it from the side, where the trap's contours can be seen.

A blockage in this curved section of the porcelain toilet base is by far the most common cause of toilet clogs. When too much debris is forced through the toilet bowl, the trap section is where the blockage usually occurs. Sometimes, the toilet trap is just partially blocked, in which case the toilet may still flush, but the water will drain out more slowly than usual. Partial clogs usually lead to complete clogs, however, as any homeowner will learn if the toilet bowl overflows completely, sending wastewater down onto the bathroom floor.

How to Fix It

A toilet plunger can often force a partial clog in the toilet trap to move through to the branch drain and onward to the main drain. If this doesn't work, 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 equalize pressure in the system and prevent water from siphoning out of the drain traps, which can release sewer gas into the home. The vent pipes are an extension of the drain pipes, running up through the roof to keep the pressure stabilized within the drain system. 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.

How to Fix It

To verify that the problem lies with the vent pipe, have one person flush the toilet while another individual on the roof holds their hand over the vent extending up through the roof above the bathroom. If there is no suction from the vent, then it is blocked and will need to be cleared with a plumber's snake. It's not uncommon for leaves or other debris to fall into a roof vent, which is usually easy to clear out. Alternately, the vent could be blocked at the outlet and simply needs to be cleaned by hand to resolve the situation.

Work on the roof is inherently dangerous, so if you have any concerns about your ability to perform this work, call a plumber for help.

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, which can cause toilets and other plumbing fixtures to drain slowy—or not at all. 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.

How to Fix It

If the problem with a main sewer line is infiltration by tree roots, it's often possible to have the lines cleared with a special motorized auger that scours the inside of the drain pipe with a flexible cable fixed with a cutting head. This is best handled by a professional who specializes in this work, although it is also possible to rent the tool yourself.

But repairing punctures, collapses, and other forms of damage to the main sewer line is almost always beyond the skill level of a DIY homeowner, as it can require major excavation work. Call a plumber or sewer contractor to address this problem and be prepared to have the main sewer line dug up and replaced. And have your checkbook or credit card handy; this is among the most expensive of all home repair projects.

Ineffective Low-Flow Toilet

Low-flow toilets are excellent options that help to reduce unnecessary water usage and also lower the water bill. There are many different styles of water-saving toilets, including dual-flush models that offer one level of flush for liquid wastes, and a second more vigorous flush for solid wastes. Whatever the style, water-conserving toilets can be prone to clogging issues because the flush incorporates less water to push the toilet paper and waste through the toilet trap and into the drainpipe. The problem is especially pronounced with early-generation models that are less efficient than more recent designs. Even when it appears to be in good shape, if the toilet clogs repeatedly, there's a good argument for upgrading.

How to Fix It

This issue can be mitigated by encouraging the practice of flushing only small amounts of toilet paper and waste at a time. This can be quite inconvenient, though, so it's better to simply upgrade to a new low-flow toilet with an improved design that can handle the demands. Recent designs, for example, use pressurized air to force a relatively small amount of water down through the bowl at a higher speed, making them just as effective as standard toilets. If you have a toilet that seems to clog all the time, this upgrade is well worth the cost.