Why Your Toilet Flushes Slowly and Gurgles, and How to Fix It
We have all been there at some point in our lives.
You press down on the flush handle, expecting a swift, satisfying swoop of water, but instead, the bowl fills up way too high, drains at a snail’s pace, and finishes off with a dramatic, mysterious gurgle.
It is enough to make anyone pause and stare into the porcelain bowl, hoping it does not suddenly overflow onto the bathroom floor.
The good news is that many slow-flushing toilets have a problem you can fix yourself.
In this post, we’ll show you what to do if your toilet flushes slowly and gurgles.
What Causes A Toilet To Flush Slowly And Gurgle?
A toilet needs enough water and air to flush properly. When something interferes with the flow, the toilet may drain slowly, bubble, or make a gurgling sound.
Here are the main causes behind this we see all the time:
- Partial clog in the toilet trap or drainpipe
- Blocked plumbing vent
- Clogged or restricted main sewer line
- Low water level in the toilet tank
- Mineral buildup around the rim holes or siphon jet
- Problems with the toilet’s flush valve or flapper
Also Read: Running Toilet? Here’s How to Fix It
How To Fix A Toilet That Flushes Slowly And Gurgles
Now that you know what might be going on under the surface, it is time to roll up your sleeves and fix it. Work through these steps one by one:
#1 Stop Flushing If The Water Rises
If the toilet bowl starts filling higher than normal when you flush, stop pressing the handle.
A partial clog can prevent water from draining quickly, and another flush may send it over the rim.
If the water is still rising, turn the shutoff valve behind the toilet clockwise to stop the supply. You can also lift the tank lid and push the flapper closed if necessary.
Give the water a little time to drain. If it stays high, remove some water with a bucket so you have room to work without making a mess.
This step sounds obvious, but it is easy to ignore.
#2 Try A Toilet Plunger
A toilet plunger is usually the best first fix for a suspected clog.
Use a flange plunger designed for toilets, rather than a flat sink plunger. The extended rubber flange fits into the drain opening and helps create a seal.
- Place the plunger over the opening at the bottom of the bowl
- Make sure the rubber flange is covered with water, adding a little if needed
- Push down gently at first to remove trapped air, then pull up firmly
- Repeat this motion several times while keeping the seal in place
After about 10 to 15 plunges, lift the plunger and see how the water behaves.
If the water suddenly swooshes down the drain with a satisfying gulp, congratulations! You likely just dislodged a minor clog right in the main trap.
If the toilet still gurgles, try another round of plunging.
Also Read: Signs You Need Professional Drain Cleaning Services
#3 Check The Toilet Tank
If plunging does not help, take a look inside the toilet tank. The water should fill to the marked waterline, usually about an inch below the top of the overflow tube.
A tank that does not fill high enough may not provide enough water for a strong flush.
Check the fill valve and adjust it according to the manufacturer’s instructions. Some valves have a small adjustment screw or clip that lets you raise the water level.
Next, press the toilet handle and watch the flapper. It should lift enough to let the tank water rush into the bowl.
A loose chain, worn flapper, or faulty handle can prevent the valve from opening fully.
If the tank is filling normally and the flapper lifts properly, the slow flush may be caused by a clog or mineral buildup instead.
#4 Clean The Toilet Rim Holes
Have you ever taken a close look under the inside rim of your toilet bowl?
That is where small holes feed water from the tank straight into the bowl to initiate the swirl that pulls everything down.
Over time, hard water minerals, scale, and bacteria build up inside those tiny openings, choking off the flow of water and making your toilet flush slowly and gurgle.
Grab a small hand mirror to inspect the underside of the rim if you want to see what is going on up close.
If those ports look crusty or blocked, pour a liberal amount of warm white vinegar into the tank overflow pipe and let it sit for a couple of hours to dissolve the mineral deposits.
Afterward, use a small stiff brush or a piece of bent wire to carefully scrub inside each small hole.
#5 Use A Toilet Auger For A Stubborn Clog
A toilet auger is the next step when plunging does not clear the blockage.
It has a flexible cable that reaches into the toilet trap and can break up or retrieve material that a plunger cannot move.
Place the auger’s curved end into the toilet drain. Turn the handle clockwise to feed the cable through the trap. You may feel resistance when the cable reaches the blockage. Continue turning gently, allowing the cable to work through the obstruction.
Once you have worked the cable in, turn the handle in the opposite direction to retract it.
Remove any debris that comes out, then test the toilet with a small amount of water first.
If the auger does not reach the blockage or the toilet continues to gurgle, the problem may be farther down the drain.
#6 Check For A Blocked Vent Pipe
A blocked vent pipe can cause a toilet to gurgle even when the toilet itself is not clogged.
When the vent is blocked by debris, leaves, or other material, the plumbing system may struggle to balance air pressure.
You might hear bubbling from the toilet, notice a slow flush, or hear gurgling from a nearby sink when the toilet drains.
A vent problem is more likely when plunging and augering have not fixed the issue. You may also notice that several fixtures in the house make similar sounds.
Clearing a plumbing vent can require roof access or specialized equipment. It is usually best to have a plumber inspect the vent instead of climbing onto the roof yourself.
Also Read: How Often Should You Have Your Sewer Line Cleaned?
#7 Call A Plumber If Multiple Drains Are Affected
If the toilet is slow and gurgling, but your sink and bathtub are also draining slowly, it is time to think beyond the toilet.
A blockage in the main drain or sewer line can affect several fixtures at once.
You may notice:
- Water backing up into the tub when you flush
- A foul smell from drains
- Several toilets making bubbling sounds
These are signs that the plumbing system may have a larger blockage. Repeatedly plunging one toilet will not solve a problem that is farther down the line.
A plumber can inspect the drain, identify the location of the blockage, and use the appropriate equipment to clear it.
If you have a septic system, they can also help determine if the problem is related to the septic tank or drain field.
Bottom Line
A toilet that flushes slowly and gurgles often has a partial clog, a low tank water level, or mineral buildup around the rim.
Start by stopping the flush if the water rises, then try a toilet plunger and check the tank.
If the problem continues, a toilet auger may clear a stubborn blockage.
Gurgling from several drains, water backing up into the tub, or repeated slow flushing can point to a vent or main drain problem that needs a plumber.
Fast. Honest. Local.
That’s Believe Plumbing.
