Yes. When a tub, shower, sink and toilet all slow or back up together, the blockage is usually in the main sewer line that every drain shares, not in one fixture. Stop using water, and check whether neighbors or a street manhole are affected to learn whether it is your line or the city's.
Why one blockage hits several drains
Every drain in the house eventually empties into one sewer line. Waste from each fixture flows into that shared pipe. If the shared pipe is blocked, water has nowhere to go, so it rises to the lowest opening in the house. That is why sewage often shows up first in a ground-floor tub, a shower or a floor drain, and why flushing one toilet can make water appear in another fixture.
The EPA says sewer overflows can be caused by blockages, line breaks, and sewer defects that let stormwater and groundwater overload the system, and that overflows can back up into homes. In the EPA's 2004 Report to Congress, which breaks down reported blockage events in public sewer systems, grease accounted for 47 percent, debris 27 percent, roots 22 percent, and roots plus grease 4 percent. The City of Phoenix says the same about its own pipes: grease is the most frequent cause, and roots from trees and invasive shrubs are next.
Signs it is the main line
- More than one drain is slow or backed up. The classic sign.
- Gurgling in a drain when another fixture runs. Trapped air is being pushed through water in the traps.
- A toilet bubbles or a tub rises when the washer drains. The washer's flow has nowhere else to go.
- Sewage or water in the lowest tub or floor drain. It comes up at the first opening it finds.
- A sewer smell around drains. See the first signs of sewer gas poisoning if the smell is strong.
Phoenix tells residents to watch for reduced drain flow and to have a plumber inspect if a blockage is suspected. Our page on signs of a sewer backup has the fuller list.
Whose pipe is it: yours or the city's
Most of the time it is the private line. In Phoenix and Mesa, the property owner is responsible for cleaning, maintaining, unstopping and repairing the pipe from the house to the public sewer, and the city handles the main in the street. There is one exception for broken pipe in the street or alley for some homes, covered in who is responsible for the sewer line in Phoenix.
To tell whether the city's main is involved, look for these clues:
| What you see | Points to |
|---|---|
| Only your house is affected | Your private line |
| Neighbors on your street have the same backup | The city main |
| A manhole in the street or yard is overflowing | The city main |
| The cleanout is full of standing water or waste | A blockage downstream of the cleanout |
| The cleanout is empty and dry | A blockage between the house and the cleanout |
The cleanout rows are a rule of thumb, and opening a cleanout on a blocked line can release sewage, so leave that to a plumber unless you know how to do it safely.
If a manhole is overflowing, call the city. Phoenix Water Services takes calls at 602-262-6691 during business hours and 602-261-8000 after hours and on weekends. Mesa's Wastewater Collection emergency line is 480-644-2262.
### What Mesa does when you call
Mesa's Sewer Blockage Inspection and Removal Service sends a city technician to check whether the main is flowing freely. If it is, the blockage is in your service line. The form says the homeowner has to provide access through a cleanout or exposed line. Mesa's form (revision 6/2024) lists a $185 fee for the service, payable regardless of result, so check the current fee. Ask your own city what it offers before you call, because rules and fees vary from city to city.
### When it is not the main line
Not every multi-fixture problem is the sewer line, and it helps to rule the other causes out before you assume the worst. A branch drain that serves a bathroom group can block without touching the kitchen. A blocked vent can slow drains and make them gurgle, and Wisconsin's health department points to roof vents plugged with leaves or nests. The pattern helps: if the kitchen sink and a bathroom on the far side of the house both act up, suspect the main line. If only the bathrooms do, suspect a branch. A plumber sorts this out with a camera and a cable. Ask which pipe was cleared, and where the blockage sat, so you know whether the fix reached the shared main or only one branch. That detail decides whether a repeat is likely, and it is worth having in writing.
### Three examples of how it plays out
These are made-up examples to show the pattern, not real jobs.
The whole house is slow after a long run of laundry. The tub gurgles, and the toilet is sluggish. The cleanout is full. Roots or grease have narrowed the main line. The fix is cleaning it, then a camera to see why.
Only the guest bath and hall bath are slow. The kitchen and laundry are fine. That points at the branch serving the bathrooms, or a vent, rather than the main.
The whole street is backing up at once. Neighbors say the same thing, and a manhole is running. Call the city. Your own line may be fine.
What to do right now
- 1Stop using water. No flushing, showers, laundry or dishwasher. Every gallon you add goes to the lowest drain.
- 2Keep people and pets away from any sewage that surfaced. It carries bacteria. Clean-up of anything beyond a small amount is a job for a professional.
- 3Check the street. Ask a neighbor. Look for an overflowing manhole. If so, call the city.
- 4Find your cleanout. The guide to sewer cleanouts shows what to look for. Do not open it unless you know how and can keep the overflow away from the house.
- 5Call a plumber for a camera inspection. Clearing the line without finding the cause invites a repeat.
### Do not rely on drain cleaners
Pouring drain chemicals into a line that is blocked all the way to the main will not reach the blockage and can leave a hazard standing in the pipe. A plumber's cable or jetter goes to the blockage itself. See what hydro jetting is.
What the plumber is looking for
Once the line is clear, the camera answers the question that matters: why did it block? The usual answers are grease, debris, and roots. If roots are the cause, does hydro jetting keep tree roots from coming back explains why a cleaning alone often is not enough. If the camera shows damage, full reline, partial reline or nothing walks through the repair choices. To prevent the next one, use the routine in how to maintain your sewer line to prevent backups.
Insurance is another question people ask right away. Our page on whether homeowners insurance covers sewer backup explains what to check.
HQ Plumbing offers 24/7 emergency service, free estimates and upfront pricing. If sewage is coming up in the house, that is the time to call.