Water is coming up out of the shower drain or the toilet, and it is not clean.
This guide explains what a sewer backup is, what usually causes one, what to do in the first hour, who cleans it up and how to stop it happening again. It is part of the water damage guides for Huntington Beach homeowners.
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In short
A sewer backup is wastewater flowing the wrong way, up through the lowest drains in a home, because the pipe between the house and the street is blocked or the public main is overloaded. It is fixed by clearing or repairing the blockage, then removing everything the sewage touched.
This guide is general information, not legal, insurance or medical advice.
A sewer backup happens when wastewater cannot leave the house, so it rises back up through the lowest fixtures. Every drain in your home joins one pipe, the sewer lateral, which runs under the yard to the city main in the street. If that lateral is blocked, or if the main is full, the next flush or shower has nowhere to go. It comes up at the lowest point: a shower pan, a floor drain, a ground-floor toilet or a tub.
The water that comes up is sewage even if it looks gray. The ANSI/IICRC S500 standard classes water from a sewer backup as Category 3, grossly contaminated water, the same category as rising flood water. That classification decides the cleanup: Category 3 water is removed, not dried, and anything porous it touched is usually discarded.
A backup is different from an overflow. A single toilet that overflows because its own trap is clogged is a local problem, covered in the toilet overflow guide. When two or more fixtures back up at once, or when flushing one fixture pushes water up another, the blockage is downstream in the lateral or the main.
Most backups come from a blocked or broken lateral on the property, and the rest from problems in the public main. The common causes:
Tree roots. Roots find the joints in an old lateral and grow inside it until the pipe is choked. The City of Huntington Beach sewer lateral page says that if a sewer line needs frequent cleaning or root removal, it may indicate a sewer lateral break or tree root intrusion.
Grease and wipes. Cooking grease cools and hardens on the pipe wall; "flushable" wipes do not break down and snag on roots and rough joints. Orange County's health agency traced a May 2025 ocean water closure at the Talbert Channel outfall to a 4,000 gallon spill from a roots-and-grease blockage in a Costa Mesa sewer line.
The pattern of the backup points to the cause. Sewage rising only at the lowest fixture, with the rest of the house draining slowly, suggests a partial lateral blockage. A sudden backup in several homes on the block during a storm points to the main.
Stop using water, keep people and pets out, and call a plumber before you clean anything. The order matters.
| Step | What to do |
|---|---|
| 1. Stop adding water | Do not flush, run a tap, use the washer or the dishwasher. Every gallon goes back to the lowest drain. |
| 2. Keep out | Close the room. Keep children and pets away. Sewage carries bacteria and other pathogens. |
| 3. Cut power to wet areas | If water has reached outlets, cords or appliances, turn off the power at the main breaker. OSHA’s flood guidance says to turn off the power at the main breaker if water has been present anywhere near electrical circuits and never to touch electrical equipment if the ground is wet. |
| 4. Call a plumber | A plumber clears the lateral or finds the break with a camera. Sewage keeps rising until the blockage is cleared. |
| 5. Report a possible main problem | If neighbors have the same backup, or sewage is surfacing at a manhole or in the street, call the City Utilities Division at (714) 536-5921 in business hours; the City’s Water and Sewer page directs after-hours emergencies to the Police Department at (714) 960-8825. |
| 6. Photograph everything | Take photos and video before anything is moved or cleaned. Note the time and which fixtures backed up. |
| 7. Do not spread it | Do not walk sewage through the house. Do not use a household vacuum on it. |
The City's lateral page adds one point homeowners miss: a blocked line often needs cleaning at once, and residents should not wait for any claims process to finish before getting it cleared.
If you plan to file an insurance claim, know that most standard homeowners policies exclude sewer and drain backup unless you bought an endorsement. The insurance guide covers that.
Sewage cleanup is a job for a restoration contractor, not the homeowner and not the plumber. The EPA's mold cleanup page says that if the water or mold damage was caused by sewage or other contaminated water, you should call in a professional. The plumber's job ends when the pipe flows; the contractor's job is everything the sewage touched.
That job usually looks like this:
Removal. Porous materials that touched sewage are cut out and bagged: carpet and pad, saturated drywall and baseboards, insulation, particleboard cabinet bottoms. The EPA's flooded homes guidance lists mattresses, cloth upholstered furniture, cushions and pillows, leather furniture, wood veneer furniture and medicine among the items to remove after contaminated water, and photos, books, bedding, rugs, solid wood furniture and appliances as items that may or may not be saved.
Drying. Only after the contamination is gone does drying start. The EPA notes that when things remain wet for more than two days they usually get moldy, so the mold guide applies from here on.
Crews wear protection for a reason. OSHA lists untreated raw sewage among the biohazards in floodwater and recommends hand, eye and respiratory protection with an N-95 respirator for the mold and cleanup phase. The EPA warns that contact with contaminated flood water can cause wound infections and rashes. A homeowner with gloves and a mop cannot safely handle a room of sewage, and materials that look clean after wiping are still contaminated inside.
The what can be saved guide explains how the water category changes what stays and what goes.
You prevent the next backup by finding out why this one happened and fixing the pipe, not just clearing it. A plumber who only augers the line has bought you months, not years, if roots or a broken joint are the cause.
A camera shows roots, offsets, bellies and breaks, and where they are. In Huntington Beach the City's program requires a cleaned and video-inspected lateral before it decides whether a repair is on its side of the property line, and the owner pays for the initial inspection.
Options are spot repair, replacement, or slip lining, which pulls a new liner through the old pipe. The City lists slip lining as a repair method that can keep a parkway tree in place, with the homeowner paying for the section on private property.
Grease goes in the trash once it cools. Wipes go in the trash, whatever the packet says.
A backwater valve on the lateral lets wastewater flow out to the street and closes when flow reverses, so a main blockage surfaces outside instead of in your shower. It matters most when fixtures sit low relative to the street.
The cleanout is the capped pipe near the foundation or in the yard. A plumber needs it to clear and inspect the line without pulling a toilet.
Gurgling drains, water rising in the shower when the toilet flushes, and a sewage smell in the yard are warnings that the lateral is partly blocked.
In January 2008 the City of Huntington Beach adopted a sewer lateral policy that splits responsibility at the property line. The City's Sewer Lateral Program states that the City is responsible for the portion of the sewer lateral that runs from the City-owned sewer main to the private property line, including the public right-of-way, and that property owners are responsible for all repair and maintenance costs for the portion of the sewer lateral located on their private property. To use the program you report the problem to the Utilities Division at (714) 536-5921, have the lateral cleaned and video-inspected at your own initial cost, and let City staff review the video to decide whether the repair falls in the right-of-way. If it does and a tree must come out, the City performs the repair at its expense and reimburses the inspection cost.
Sunset Beach is different. Its sewers belong to the Sunset Beach Sanitary District, and the City reported in 2025 that most of that district's collection system dates to 1935, that its Broadway pump station and 1983 force main were at the end of their service life, and that construction of a new gravity sewer along Warner Avenue and the Sunset Greenbelt began in October 2025.
Call as soon as the plumber has the line flowing, or at the same time. Sewage in a home is a Category 3 loss whatever the size, and the contamination does not wait for the drying to start. HB Water Damage is an independent referral service: it is contractor-neutral and connects callers with independent restoration contractors for sewage backup cleanup in Huntington Beach. The contractor, not this site, sets the scope and the price.
Water in your home right now? Call and get connected to an independent restoration contractor who covers your street.
A sewer backup is treated as an emergency because sewage is Category 3 water and it keeps rising while water is used. Stop using water, keep out of the room and call a plumber right away.
The owner is responsible for the lateral on private property. In Huntington Beach the City is responsible for the section from its main to the property line, including the right-of-way, under its 2008 policy.
The EPA says to call a professional when water damage was caused by sewage or other contaminated water. A small splash on a tile floor can be wiped and disinfected with gloves on; a flooded room cannot.
Most standard policies exclude water that backs up through sewers or drains. A sewer or drain backup endorsement adds that coverage. Check your declarations page.
Sewage surfaces at the lowest open drain. A shower pan or floor drain sits lower than a toilet bowl, so a downstream blockage shows there first.
If neighbors have the same problem, or sewage is surfacing at a manhole or in the street, the main is the likely cause. Report it to the City Utilities Division; after hours the City directs callers to the Police Department line.
One call reaches an independent restoration contractor who covers your area. The contractor handles the inspection, the estimate and the work.
Independent line. No charge to you. Calls may be recorded.
