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Why Are My Drains Gurgling? Causes & Cures

Gurgling noises emanating from your sink can be a source of worry, but is it cause for concern? Is it a sign of a larger problem or should you call a plumber?

Most often the gurgling is just a sign of normal drainage. However, if you notice that the noise is getting louder or occurring more frequently, there is action you can take to prevent it from becoming a larger problem.

Problems with noisy plumbing are typically caused by one of four reasons, including blocked drains, main sewer line clogs, a blocked ventilation system, or blocked or damaged P-traps. 

In this article, we will explain why these issues occur, how to find the source of the issue, how to fix the problem, and effective methods to prevent future gurgling noises.

Key Takeaways

  • Gurgling in pipes can be caused by obstructions, improper ventilation, malfunctioning plumbing fixtures, or clogged or damaged plumbing traps. 
  • Clogs are the most common cause, however, they can be caused for a variety of reasons.
  • Depending on what caused the blockage and where it has occurred will determine the best way to fix the problem.

Why Are My Pipes Gurgling?

Gurgling in drains is a common plumbing problem that often results from either inadequate venting or partial pipe or drain clogs. These partial obstructions hinder water drainage and cause a vacuum to form, trapping air bubbles. When this trapped air is displaced by draining water, it creates a gurgling noise.

Locating where the problem has occurred is key to fixing the issue.

The noises you hear in your plumbing system may be caused by one of the following issues listed below.

  1. Partially Blocked Drain
  2. Partially Blocked Main Sewer Line
  3. Partially Blocked Ventilation System
  4. Partially Blocked (or Damaged) P-Trap

1. Partially Blocked Drain

A partially clogged drain can cause a gurgling sound, particularly if you can trace the noise to a specific drain. 

If you have a noisy kitchen sink, or shower drain, this type of blockage typically occurs due to the buildup of debris and foreign objects within the drain system. Food particles, hair and soap scum are among the most common culprits for clogged drains. These partial clogs often trap air, forming an air pocket, the gurgling are caused by this air being displaced by draining water.

In addition to the noise, other symptoms may include slow drainage and visible air bubbles.

A gurgling sink drain should be taken as a warning before you end up with a completely blocked drain.

2. Partially Blocked Main Sewer Line

A blocked main sewer line can cause gurgling noises in plumbing fixtures.

Blocked sewer lines can be caused by multiple issues such as those given below.

  • Tree Roots. Tree roots can penetrate the sewer pipes, causing obstructions that hinder the flow of wastewater
  • Aging pipes. Pipes made from materials like cast iron may deteriorate over time, leading to cracks, collapses, or sagging that obstruct the flow of sewage
  • Solid obstructions. Flushing items down toilets that are not designed to be flushed—such as diapers, paper towels, or feminine hygiene products—can lead to clogs in the main sewer line. Similarly, pouring grease into drains should be avoided as it solidifies inside pipes over time 
  • Heavy rainfall or Flooding. Flooding can overload the sewer system and cause the main city sewer line to back up in your drain line, potentially leaving behind debris.

Common symptoms of a blocked sewer line include multiple noisy drains and slow drainage.

3. Partially Blocked Ventilation System

Blocked ventilation pipes are another common cause of gurgling noises in your home.

A properly functioning ventilation system is crucial for the proper flow in your drain pipes. It allows air to enter the drain lines, preventing negative pressure and facilitating smooth water flow. However, when debris such as leaves, sticks, or bird nests obstruct drain vents, it can lead to clogs in the system.

Additionally, aging vent pipes may corrode or collapse over time, also leading to blockages.

These blockages whether caused by debris or damaged pipes, create negative air pressure, trapping air in the system. These trapped air pockets caused by these blockages will often cause gurgling drains and fixtures. In addition to strange noises, all the drains in your home may drain slowly.

4. Partially Blocked or Damaged P-Trap

A blocked or broken P-Trap can be the cause of strange gurgling noises. 

The plumbing trap plays a crucial role in preventing noxious sewer gases from entering your home. This u-shaped curved pipe, found beneath sinks and other fixtures, creates a barrier by forming a water seal that blocks bad odors.

One common cause is the accumulation of debris and solid materials within the P-trap causing blockages. These blockages hinder the proper flow of air through the trap and result in unpleasant sounds.

In addition to blockages caused by debris accumulation, damage due to wear and tear can also lead to noises. The p-trap may become cracked or worn out over time, allowing air to escape or enter where it shouldn’t. This disruption in the seal produces gurgling sounds and allows sewer gas to enter your home as a result.

An incorrectly installed p-trap can also be the cause. If not correctly installed or sealed tightly enough, air may find its way into spaces it shouldn’t be able to access. 

How to Fix a Gurgling Sound Coming from Your Drain?

If you want to fix your gurgling pipes you will need to determine the source of the issue. Start by identifying if the problem is affecting multiple sinks and fixtures throughout your home, or if the sound is coming from one location.

  1. How to fix Bubbling Kitchen or Bathroom Sinks?
  2. How to unclog a Sewer Line?
  3. How to Clear a Gurgling Vent Pipe?
  4. How to fix a Blocked P-Trap?

1. How to fix Bubbling Kitchen or Bathroom Sinks?

If your kitchen or bathroom drain is bubbling and making noises, its time to do some drain cleaning. The easiest solution is to use a mix of baking soda and vinegar to try and unclog the drain. Pour a cup of baking soda down the drain, followed by a cup of vinegar and leave for 15 mins. Follow this by pouring hot water to flush out the debris.

If the sink or garbage disposal is still not draining satisfactorily consider using a plumber’s snake or a plunger to mechanically remove the clog. 

2. How to unclog a Sewer Line?

To unclog a sewer line, there are several potential solutions you can try. If you suspect a minor clog, you can use a plumber’s snake or auger. These tools can be inserted through clean-out access points to dislodge the buildup and restore proper flow.

For more stubborn obstructions, high-pressure hydrojetting techniques can be effective. This method involves using a specialized machine that propels highly pressurized water into the sewer line to break up and flush away the obstruction.

If you’re dealing with severe clogs, pipe damage, or suspect tree root invasion, it is recommended to call a  professional experienced plumber. These professionals have the expertise and specialized equipment needed to thoroughly clean out or repair the blocked sewer line.

3. How to Clear a Gurgling Vent Pipe?

To clear a gurgling vent pipe, homeowners can follow these steps.

  1. Start by checking the vent pipe on the roof for any visible obstructions. Ensure that there are no leaves, debris, or other obstructions restricting the airflow.
  2. Use a plumbing snake or auger to remove any obstructions from the vent pipe. Gently insert the snake into the pipe and rotate it to dislodge any debris.
  3. If you’re unsure about using a plumbing snake or if the problem persists, consider enlisting the help of a professional plumber. They have experience in dealing with vent pipe issues and can ensure safe and effective clearing.
  4. Inspect all vent openings in and around your home to ensure they are free from debris or obstructions. Check vents on the exterior walls as well as those connected to appliances like toilets and sinks.
  5. Clean and maintain your vent pipes regularly. Remove any buildup of dirt, grime, or mold using appropriate cleaning solutions. Regular maintenance helps keep your plumbing system functioning properly.

4. How to fix a Blocked P-Trap?

To fix a blocked P-trap and address gurgling sounds in plumbing fixtures, follow these steps:

  1. Place a bucket or basin under the P-trap to catch any water or debris that may spill during disassembly.
  2. Using pliers or a wrench, loosen the slip nuts that connect the P-trap to the adjacent drain pipe.
  3. Carefully remove the P-trap, taking care not to damage any surrounding pipes or fittings.
  4. Using an old toothbrush or wire brush, clean out any hair, grease, food or other debris from inside the P-trap.
  5. Reassemble the P-trap by securely tightening the slip nuts. Be cautious not to overtighten as it may result in leaks.

How to Prevent Gurgling Pipes & Drains?

There’s many ways to prevent gurgling pipes and drains, which we’ve given in the list below.

  • Proper Disposal: Avoid disposing of items that can clog drains, such as grease, food scraps, hair, and non-flushable items. Use a drain strainer or filter to catch debris.
  • Flush with Hot Water: Periodically flush your drains with hot water to help dissolve and clear away any buildup of soap scum and grease.
  • Clean P-Traps: Regularly clean the P-traps under sinks and fixtures to prevent debris accumulation.
  • Check Ventilation: Ensure that your plumbing system’s vent pipes are not obstructed.
  • Use Enzyme Cleaners: Consider using enzyme-based drain cleaners to help break down organic material and keep drains clear.
  • Tree Root Prevention: If you have trees near your sewer lines, consult with a professional to prevent tree root infiltration into the pipes.
  • Install Backflow Preventers: Install backflow preventers on your drains to stop sewage backup and prevent gurgling caused by sewer line problems.

Frequently Asked Questions about Gurgling Drains

Below we answer some common questions about noisy plumbing systems

Why is My Drain Gurgling When Not In Use?

The most common reason for drain gurgling even when not in use is a dry p-trap. When drain fixtures are not used frequently, the water inside their respective p-traps can evaporate over time, resulting in gurgling noises.

Why Does the Tub Gurgle When the Toilet Flushes?

The likely cause is that the shared vent system between your bathroom fixtures has become clogged with debris. This limited airflow through the vents can result in pressure differences, causing air bubbles and gurgling sounds in the tub drain when you flush the toilet.

Why Does the Sink Make a Gurgling Noise When the Toilet is Flushed?

The likely cause is that the shared vent system between your bathroom fixtures has become clogged with debris. This limited airflow through the vents can result in pressure differences, causing air bubbles and gurgling sounds in the bathroom sink drain when you flush the toilet.

Why is My Kitchen Sink Gurgling But My Drains Seem Fine?

This may be the result of a dry p-trap if you have not used your kitchen or bathroom sink for a while. It can also be the result of a blockage in a specific vent pipe connected to that sink.

Why is Water Coming Up My Bathroom Sink?

Water coming up your bathroom sink is often due to a clogged drain, a blocked P-trap, or a more serious issue like a main sewer line clog or ventilation problems.

About the author

An accomplished plumber with more than 15 years of experience in the industry, David "Fitz" Fitzgerald began as an apprentice and steadily worked his way up to become a fully licensed and certified master plumber.

With extensive training in all aspects of plumbing. David is well-versed in the installation, repair, and maintenance of plumbing systems, including pipes, fixtures, and appliances, and is able to troubleshoot and solve even the most complex plumbing issues.

He loves to share his wealth of knowledge and looks forward to engaging with the community here on No Hassle Plumbing.

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