Home / Common plumbing problems / Gurgling drain
Plumbing problem
Why is my drain gurgling?
The short answer
Official sources link a gurgling drain to a blocked plumbing vent that pulls water from the traps (NDSU Extension), a blockage in the drain or main line (Town of Simsbury), or, on a septic system, a failing system (EPA). The number of drains affected is the first clue.
What people usually report
A bathroom sink that gurgles when the tub drains, a kitchen sink that bubbles while the dishwasher or washing machine empties, or a shower drain that glugs after the water is off. Often the drain is also a little slower than it used to be, and sometimes there is a sewer smell.
What official sources say the causes can include
- A blocked vent. The roof vent lets gases from the sewer or septic system escape. When it is blocked, water is pulled from the traps to replace the air flow, and gurgling or a poorly flushing toilet can be the first sign. NDSU names snow over the vent stack as one cause (North Dakota State University Extension) and frost forming at the top of the vent in cold weather as another (North Dakota State University Extension).
- A blockage. Slow draining or gurgling in sinks, showers, or toilets is a sign of a blockage. All drains backing up at once points to the main sewer line (Town of Simsbury, CT, Water Pollution Control).
- A septic problem. EPA and Washington’s health department both list gurgling sounds in the plumbing system with slow drains and backups as signs of septic failure (U.S. EPA; Washington State Department of Health).
Why traps matter
Drain traps hold water that keeps sewer gas out of the house. Clogged vents can lead to sewer gas backup, which NDSU says can cause illness (North Dakota State University Extension), and dried-out traps in floor drains and rarely used sinks, showers, and tubs are another way sewer gas gets in. NDSU suggests running water into those drains every three to four weeks (North Dakota State University Extension). If the gurgling comes with a smell, see sewer smell in the house.
How to find out
- Count the drains. Run each sink, tub, and shower and note which gurgle and which drain slowly. One drain points to that fixture; all of them backing up at once points to the main line (Town of Simsbury, CT, Water Pollution Control).
- Note the trigger. Whether it happens when another fixture drains, when the washer empties, or on its own is useful for a plumber.
- On septic, check when the tank was last pumped. EPA recommends pumping every 3 to 5 years (U.S. EPA).
Clearing a main line is priced on our drain cleaning cost page. If a toilet is the one gurgling, see gurgling toilet.
Local help
Who to contact
On a public sewer, your sewer utility can often tell you whether a blockage is in its main or your own line; its number is on your bill. On a septic system, EPA points to a septic service provider or your local health department (U.S. EPA).
For work on the pipes and fixtures inside your home, hire a licensed plumber and confirm the license before work starts. Our guide to choosing a plumber covers what to ask. License lookups for the areas our city pages cover:
- FL: Florida Department of Business and Professional Regulation (DBPR)
- IA: Iowa Plumbing and Mechanical Systems Board (PMSB), administered by Iowa DIAL
- MO: Kansas City, MO City Planning & Development (plumbing license, city-issued)
- NE: City of Omaha Building and Development Division (plumbing license, city-issued; Nebraska has no statewide plumbing board)
- NV: Nevada State Contractors Board (NSCB), Classification C (plumbing)
- OK: Oklahoma Construction Industries Board (CIB)
- TX: Texas State Board of Plumbing Examiners (TSBPE)
Elsewhere, search your state’s plumbing or contractor licensing board. Some cities issue plumbing licenses themselves.
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Common questions
Gurgling drain questions
Why is my sink gurgling but not blocked?
North Dakota State University Extension says that when a plumbing vent is blocked, water is pulled from the traps to replace the air flow, and gurgling can be the first sign. Snow over the roof vent, or frost that forms at the top of the vent in cold weather, can do it. Gurgling with no slow draining is still worth noting, especially if more fixtures start doing it.
How do I fix a gurgling drain?
The fix depends on the cause. A clog in one fixture is cleared at that fixture. A blocked vent or a main-line clog is a job for a licensed plumber, and the Town of Simsbury, Connecticut says the building’s pipes and the lateral to the sewer main are the owner’s responsibility. On septic, EPA says to contact a septic service provider or your health department.
Why is my drain making a gurgling noise?
Official sources link gurgling to three things: a blocked plumbing vent (NDSU Extension), a blockage in the drain or main line (Town of Simsbury), and, on septic, a failing septic system (EPA, Washington State Department of Health). Which drains gurgle, and whether they also drain slowly, helps a plumber tell them apart.
Sources and limits
- Washington State Department of Health, Sewage Spills: Cleaning Them Up. Checked 2026-10-05.
- Town of Simsbury, CT, Water Pollution Control, If You Have a Plumbing Blockage. Checked 2026-10-05.
- North Dakota State University Extension, Check Your Sewer Vents. Checked 2026-10-05.
- North Dakota State University Extension, Prevent Sewer Gas Backup. Checked 2026-10-05.
- U.S. EPA, Resolving Septic System Malfunctions. Checked 2026-10-05.
- Washington State Department of Health, Signs of Septic System Failure. Checked 2026-10-05.
This page summarizes guidance published by the agencies and organizations listed above. It is general information, not a diagnosis of your home or your water. Guidance can change, so check the linked source, your water utility, or your local health department before acting on it. PlumbingRepairCost is not affiliated with any agency named here. Spotted an error? Email hello@plumbingrepaircost.com and we will check it against the source.