What Causes a Toilet Backup and What You Can Do to Fix It

Ellie Brooks

Written By Ellie Brooks

Published 10/17/22
What Causes a Toilet Backup and What You Can Do to Fix It

A backed-up toilet is one of those nightmare scenarios. Homeowners who have flushed the toilet only to watch the water rise understand what true panic feels like. Even if you’re spared the horror of an overflow, having an unusable toilet in the house is a major inconvenience.

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There are a few potential causes of toilet backups. Sometimes, all you need is a plunger to solve the issue. Other times, you’ll need to enlist some professional help. In this article, we’ll review some common reasons for toilet trouble and what you can do to keep your plumbing clear.


Most Common Causes of Toilet Backups

A toilet backing up when flushed can have a few explanations. Here are the most common causes.

1. The plumbing is clogged.

Plumbing fixtures, by law, are fitted with traps to prevent the backflow of noxious sewer gases. The trap is the curved piping you have likely seen beneath sinks or behind toilets. The P-trap or S-trap that is fitted onto most toilets can become clogged with toilet paper, hygiene products, hair, or other materials. This will of course cause drainage problems, and the water level in the bowl will rise after you flush the toilet.

Clogs can also occur farther down the plumbing system. The cause of the clog may be less obvious because the blockage has likely grown over time. Often, these clogs are caused by objects and materials that should not be flushed, such as tissues, paper towels, napkins, wet wipes, oils, and grease. These are the same materials that form the fatbergs that plague municipal sewer systems.

A clog somewhere in the plumbing system is the most common cause of toilet backups. If you notice problems with only one toilet, and all other drains in the house appear to be fine, a local clog is the likely culprit.

2. The sewer line is blocked or damaged.

Sewer line blockages are another common cause of toilet and drain backups. It’s not uncommon for tree roots to impede underground plumbing. Roots are naturally drawn toward the warmth, moisture, and nutrients near sewer lines. The slow and steady growth continues over years until the roots seriously inhibit the flow of sewage of wastewater.

In some circumstances, roots will damage piping to the point that it needs to be repaired. Construction machinery, shifting ground, and corrosion over time can also cause ruptures, breaks, and collapses. Any such damage to a sewer line can cause backups in your toilets and drains.

3. The plumbing ventilation system is faulty.

A vent pipe or vent stack is a home feature that serves to regulate air pressure within the plumbing system. This vertical pipe allows for the release of harmful gases and prevents wastewater and sewage from backing up in the home’s plumbing system.

A vent pipe is usually a fixture on a home’s roof. It can become obstructed by leaves, twigs, and other debris. If the vent pipe becomes clogged, the overall plumbing system can suffer, and a plumbing backup is possible.

4. Heavy rains have overwhelmed your plumbing system.

Heavy rainfall or rapid snowmelt can cause plumbing issues as well. The deluge of water can flush debris into the sewer lines, reverse the flow within a pipe, or simply overwhelm a home’s plumbing system with too much water.

Fortunately, plumbing issues related to storms are usually short-lived. More concerning is if backups become a recurring problem whenever it rains.

How to Fix Toilet Backing Up Issues

Some plumbing backups are easy enough for the average homeowner to resolve. If the problem is isolated to one toilet, a clog is the most likely cause. A basic plunger is usually all you need, though plungers with a flange on the bottom work better to unclog toilets.

If a plunger fails to resolve the clog, a toilet auger is worth a try. In rare cases, you may need to shut off the water and remove a portion of the pipes to dislodge the blockage. Unless you’re familiar with plumbing, it’s best to leave this to a professional.

If sink and shower drains throughout the house are also gurgling or backing up, there is probably an issue with the sewer line or vent pipe. A sudden problem could be the result of a clog, storm, or pipe rupture. Plumbing issues that gradually get worse could be related to tree root blockages or vent pipe obstructions.

Reasonably handy homeowners can visually inspect the roof’s vent pipe for debris. They can also try using the main water supply controls to relieve the pressure in the sewer line. Chemical treatments are a possibility, but there is no guarantee that they will resolve the problem. Harsh chemicals can also damage plumbing and the environment. For most homeowners, whole-house backups and toilet backups with no discernible cause require the help of a professional plumber.

Are Toilets Covered Under Home Warranty Policies?

The details of home warranty coverage vary by company and policy, but it is certainly possible to find warranty protection for toilets. Liberty Home Guard’s System Guard and Total Home Guard plans, for instance, cover toilet flusher parts and mechanisms, tanks, bowls, and wax ring seals. We also cover mainline stoppages and clogs.

For a free quote or more information on all that Liberty Home Guard covers, call us at (866)-432-1283.


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