Why Is My Toilet Bubbling? Causes in Tempe Homes

By the Tempe Emergency Plumber team · Updated October 2026

What to do first

1. Stop flushing the bubbling toilet. Each flush can push more water toward a blockage and cause an overflow.
2. If the bowl is rising, turn the shut-off valve behind the toilet clockwise to stop the tank from refilling.
3. Hold off on showers, laundry and the dishwasher until you know whether the main line is involved.
4. Check the lowest drains in the home, like a tub or floor drain, for slow draining or dirty water.
5. If sewage comes up, keep children and pets away, take photos, and call to be connected with a local provider.

Why is my toilet bubbling when no one is using it?

A toilet that bubbles when no one is using it in a Tempe home is usually showing you trapped air. Water in the bowl is a seal, and when a drain or vent is partly blocked, air from the pipes gets forced up through that seal as bubbles or a gurgle.

Normal drains move water and air together. Waste flows down while air flows in through the roof vent to keep pressure even. When that balance is off, the toilet is often the first fixture to show it, because it has the largest drain and the widest water seal. The three most common causes are:

• A partial clog in the toilet trap or the branch drain right after it.
• A blocked vent on the roof, so the system pulls air through the toilet instead.
• A main sewer line problem, such as a buildup or roots, that backs up the whole house.

A single quiet bubble now and then is not always a crisis. Bubbling that repeats, or that comes with slow drains or odor, is a sign to look closer.

Is a bubbling toilet a clog in the toilet or deeper in the drain?

The quickest test is to check other fixtures. If only one toilet bubbles and every sink, shower and tub drains normally, the clog is probably in that toilet or the short pipe after it. If two or more drains are slow or gurgling, the blockage is likely further down, where those drains meet.

Watch how the bowl behaves when you flush. A bowl that rises high and drains slowly suggests a clog near the toilet. A bowl that drains but then gurgles, or a tub that bubbles when the toilet flushes, points to a shared line. Our guide on telling a clogged drain from a sewer line problem walks through more of these checks.

Why does my toilet bubble when I run the shower or washing machine?

When a toilet bubbles while the shower, tub or washing machine drains, the water from those fixtures is meeting a blockage and pushing air back up through the toilet. That usually means the shared drain line or the main sewer line is partly blocked.

Washing machines are a common trigger because they dump a lot of water fast. If you see the toilet gurgle during the washer's drain cycle, stop running laundry until the line is checked. Continuing to drain large amounts of water can turn a gurgle into a backup at the lowest fixture in the home, often a tub or shower.

Can a blocked plumbing vent make a toilet gurgle?

Yes. A blocked vent can make a toilet gurgle or bubble even when the drain itself is clear. The vent pipe lets air into the drain system through the roof. If it is blocked by debris, a bird nest or a buildup, the system pulls air from the easiest place it can find, often the toilet bowl.

Vent problems tend to show up as gurgling after other fixtures drain, a toilet bowl water level that drops on its own, or a sewer odor indoors. Clearing a vent means working on the roof, which is a fall risk. A plumbing provider can check the vent from the roof or with a camera without guesswork.

How do I know if a bubbling toilet means a sewer line problem?

A bubbling toilet points to a sewer line problem when several drains act up at once, when water comes up in a tub or floor drain after flushing, or when you notice a sewage odor inside or in the yard. Any of these means the main line may be partly blocked.

Other signs that often show up together:

• Gurgling in more than one toilet or sink.
• Water backing up in the lowest drain when the washer or dishwasher runs.
• Soggy or unusually green patches over the sewer line outside.
• Slow drains that come back soon after being cleared.

A camera inspection is the usual way to confirm what is inside the line. Learn more on our sewer line repair page.

What can I safely try before calling for help?

For a single bubbling toilet with no backup, a flange plunger is a safe first try. Use slow, firm pushes with the cup fully covered by water, then flush once to test. If the toilet still bubbles, or other drains are involved, stop and get help.

• Do use a flange plunger made for toilets, not a flat sink plunger.
• Do try a closet auger for a toilet-only clog if you are comfortable with it.
• Do not pour chemical drain cleaner into a toilet. It can splash, sit in the bowl and make the job harder for whoever opens the drain next.
• Do not climb on the roof to clear a vent. The fall risk is real.
• Do not keep flushing to see if it clears.

When is a bubbling toilet a plumbing emergency?

A bubbling toilet becomes an emergency when sewage or dirty water comes up into the home, when the only toilet cannot be used, or when water is spreading onto floors. In those cases, stop using water and call to be connected with a local provider.

If the bubbling is mild, comes and goes, and every drain still works, it can usually wait for a normal appointment. Treat it as a warning, though. Partial blockages tend to get worse over time, and it is easier to deal with them before a backup happens.

What happens during the visit?

A local plumbing provider starts by asking what you have noticed and checking how the toilet and other drains behave. They may run water, look at the vent, and use a camera to see inside the drain or sewer line.

Next, they explain what they found and the options, such as clearing a clog, cleaning the line, or repairing a damaged section. You should get a written quote before any work starts. See toilet and faucet repair and drain cleaning for more on common fixes.

What should Tempe-area homeowners know about a bubbling toilet?

Across the East Valley, a bubbling toilet often gets noticed after heavy use or a storm. The National Weather Service defines the monsoon as June 15 through September 30, and NWS Phoenix reported that the October 12-13, 2025 storms caused overflowing washes and street closures across the Phoenix metro. If your toilet started gurgling after a big storm, mention the timing on the call.

Hard water is common here too, though it affects fill valves and faucets more than drains. Mesa's 2025 report gives average hardness of about 12 grains per gallon in its City Zone and 16 in its Eastern and Southern Zones. Scottsdale says scale can clog faucets, aerators and, in rare cases, pipes. The City of Phoenix, which serves many homes in Ahwatukee and Arcadia, reports hardness of 10 to 17.6 grains per gallon.

If a backup leaves water on the floor, the Arizona Department of Health Services lists backed-up sewers among indoor moisture sources and says to remove the source of moisture before cleanup. The EPA says to dry wet areas within 24-48 hours. Arizona's insurance department advises taking photos before plumbers or restoration contractors arrive. You can look up a plumbing contractor in the Arizona Registrar of Contractors' online search; residential plumbing falls under the R-37 classification.

Whether you are in Tempe, Mesa, Chandler, Guadalupe or South Scottsdale, call (480) 439-0083 to be connected with a local provider who can check availability for your address.

Related pages

• Toilet and faucet repair in Tempe
• Drain cleaning
• Sewer line repair
• Emergency plumber in Mesa