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Why Is My Toilet Gurgling on a Septic System? 4 Likely Reasons

person flushing a toilet

Is Your toilet making gurgling noises whenever you flush? That is usually indicative of a problem in your plumbing system. Sometimes it could be a minor issue requiring a quick fix. But it could also be a symptom of a bigger problem in your septic system that only an expert could resolve.

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What Causes a Toilet to Gurgle?

The air flows through the pipes without hindrance in a functioning septic system. However, a clog in the system causes a build-up of negative air pressure (suction) in your drain line. The bubbling noises you hear are due to the suction pushing air back through the piping into your toilet bowl.

The clog could be a result of one of four reasons:

1. Blocked Plumbing Drain

plumber working with toilet leak
Image By: New Africa, Shutterstock

The plumbing drain directly below your toilet is the most obvious culprit when there is a clog in your septic system. It is the least alarming of all the possible things that could go wrong because you can solve it without breaking a sweat.

A blocked plumbing drain is often the result of a partial clog. The blockage makes the waste flow sluggishly and causes distinct gurgling noises.

Unclogging a blocked plumbing drain is straightforward if you have the right tools. For a partial clog, a plunger will get the job done.

First, seal off nearby tubs, sinks, and showers with duct tape to prevent air from escaping. Then fit the head of the plunger to the drain hole of the toilet bowl (when full of water) and pump 10 to 15 times. If the problem persists, you could be dealing with a sizable clog.

A snake tool will remove large clogs that require more pressure to dislodge. It features a long cable that extends 5 to 15 feet into your drain and a crank to help you push it in and out. The head includes chopping blades to cut through those stubborn clogs.

You may need to call a plumber if the clog is too far down for the snake tool to reach. After removing the toilet from its base, the plumber will use a motorized snake, which extends 100 feet into your drain to remove the clog.

Never use chemical draining agents to unclog the plumbing drain since they interfere with your septic line’s ecosystem. Moreover, the chemicals can damage your pipes over time, thus causing plumbing failures in the future.

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2. Blocked Sewage Piping

All the waste from the house, including the bathroom, kitchen, and laundry room, drains into the main sewer line, which then carries it to the septic tank. The gurgling noises could also be due to a blockage in these sewer pipes.

There are various reasons why your sewage pipes could clog. They include:

Flushing Debris

One of the most common causes of clogging is flushing inappropriate things, such as sanitary towels and cotton swabs. Other things you shouldn’t flush down the toilet include:

  • Cat litter
  • Cigarette butts
  • Dental floss
  • Grease and fats
  • Medications
  • Paper towels
  • Wipes

Root Infiltration

Tree roots can penetrate the sewer lines and cause a partial or entire blockage. This problem can be hard to solve since the roots will regrow after you cut them.

Shifting Ground

The seals on your sewer lines can become loose when the ground starts to shift. Debris and grime can then enter through the tiny gaps resulting in blockages.

Clogged sewage lines can be challenging to unblock, especially if you don’t know where the blockage is. That’s why you should consider hiring a professional plumber.

A specialist will first conduct a camera test to identify the blockage, then use a plumber’s auger to clear the obstructions. This tool is strong enough to even cut through roots. The plumber will also excavate and make the necessary repairs if the sewer line has collapsed or burst.

3. Blocked Drain-Vent System

close up of a dirty dryer vent
Image By: Greenseas, Shutterstock

The vent stack on your roof is responsible for dispelling the smelly odors from your plumbing system. It also balances the pressure in your plumbing pipes, ensuring that the waste and water move freely.

Leaves or other debris can clog your vent stack, creating a negative pressure that causes your toilet to gurgle. It can be hard to differentiate between a clog in the drain vent and other clogs in the system, so you may need to inspect it manually.

Clogs that sit close to the top are easy to clear since you can easily see them. However, you may have to pump water down the vent with a hose pipe for deeper clogs. If climbing the roof seems too dangerous, hire a professional plumber.

4. Over-Full Septic Tank

Gurgling in your toilet could also signal a problem in your septic tank. If the tank is too full of solids, it will block the sewer lines and hinder proper waste flow. That will result in gurgling.

Ensure a septic service professional inspects and pumps your septic tank every three to five years. Failure to do this can cause the sewage to back up to your toilet, bathroom, or sink. It can also ruin your drain field.

Leaving the septic tank unchecked for many years could endanger the health of members of your household. You could also be required to pay for expensive septic tank repairs.

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How to Prevent Your Toilet From Gurgling

man pushing button on dual flush toilet
Image Credit: FotoDuets, Shutterstock

Don’t wait for plumbing problems to appear before you take action. What may be a gurgle today could become a significant problem that will make you dig deeper into your pockets. With plumbing, prevention is always the better option.

You can take several measures to avoid blockages that may cause your toilet to gurgle. They include:

Don’t Flush Inappropriate Items

You should only flush waste, toilet paper, and water. Although the toilet may seem like a convenient trash can, flushing things that you should otherwise dump could cause blockages in your plumbing system.

Cover Your Vent Stack

Ideally, it is better not to cover the vent stack since you can offset the pressure balance and cause smelly odors to build up in the plumbing system. However, you can use a metal mushroom cap or wire mesh. These won’t interfere with the airflow and will block out debris, rodents, and birds that could cause blockages.

Conduct Regular Inspection

Don’t wait until your septic waste backs up to your toilet, shower, or sink. Hire a service professional to inspect and maintain your septic system every three to five years. That will enable you to make repairs early before they become too costly.

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Final Thoughts

The gurgling noises your toilet makes while flushing is usually a sign of clogging within the plumbing system and should worry you. Blockage can occur in the plumbing drain, the main sewer line, or the vent stack. But it could also be a result of overflow in the septic tank.

Some minor clogs are straightforward to unblock if you have the right tools. However, you should hire a professional plumber if the gurgling persists or the problem seems too challenging or dangerous to repair. Remember, the earlier you resolve the issue, the better.

Featured Image Credit: Miriam Alonso, Pexels


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