In depth
Sewage Backup Cleanup in Chicago: how the job actually runs.
A sewage backup in Chicago rarely starts with a broken pipe in your house. It starts with a summer thunderstorm. A short, intense downpour fills the combined sewer under the street faster than it can drain, and the mix of storm runoff and raw sewage looks for the lowest opening it can find. In most neighborhoods that is a basement floor drain.
We provide sewage cleanup across Chicago and the surrounding suburbs to the IICRC S500 standard for Category 3 water. This page covers why backups happen here, what the protocol requires, what has to be removed, how the space is cleared, and what your Illinois policy needs to say for the bill to be covered.
Why Chicago basements get sewage backups
Most of the City of Chicago and the older inner suburbs, including Oak Park, Cicero, Berwyn and parts of Evanston, run storm water and sanitary sewage in the same pipes. That is a combined sewer system. In a heavy rain it surcharges and backs up through floor drains, toilets, showers and laundry tubs in the basements along the line.
The Metropolitan Water Reclamation District’s Tunnel and Reservoir Plan, better known as the Deep Tunnel, with the Thornton reservoir (2015) and the first stage of McCook (2017), reduced how often this happens. It did not stop it. On July 2, 2023, up to about 9 inches of rain fell on parts of the West Side, Cicero and Berwyn, thousands of basements flooded, and Cook County received a federal disaster declaration. Neighborhoods like Austin were among the hardest hit. In two-flats and three-flats with a garden unit below grade, a backup is not a storage problem but someone’s home.
The Category 3 protocol
The IICRC S500 standard sorts water into three categories: Category 1 clean supply water, Category 2 gray water from appliances or clean water that has sat, and Category 3 grossly contaminated water from sewage, river flooding or anything that came through a sewer line. Combined sewer backup is Category 3 regardless of how clear it looks.
Personal protective equipment
Every technician in the affected area wears waterproof boots, gloves, eye protection and an N95 or better respirator, with disposable coveralls when the water is deep or there is splash risk. We contain the basement from the rest of the house with plastic sheeting and set up a clean-dirty transition at the stairs so contaminated boots and bags do not travel through the kitchen. Keep children and pets upstairs until the space has been cleared.
Pumping and extraction
Standing sewage is pumped with submersible units and discharged to a working sewer connection, never to the yard or the street. Extractors then take the remainder off the floor. Our water extraction service covers the equipment; on a sewage job everything the water touched is treated as contaminated, including the hoses.
What must be removed
Porous materials that touched Category 3 water cannot be dried and kept, and most adjusters expect them removed. Bagged for disposal:
- Carpet and carpet pad
- Drywall and paneling below the water line, typically cut 12 to 24 inches above it so the wet edge is gone
- Fiberglass and cellulose insulation in the wall cavity
- Particleboard and MDF cabinets, baseboards and trim
- Upholstered furniture, mattresses, area rugs
- Cardboard boxes and their contents, books and paper records
- Any food, including sealed cans that sat in the water
What can be cleaned and kept
Non-porous materials can be cleaned, disinfected, dried and kept: concrete floors, block and poured foundation walls, framing once the drywall is off, metal shelving, sealed plastic bins, tools and sealed hard furniture. Items stored above the water line usually need only a surface clean.
Disinfection and clearance
Once the water and the porous materials are out, we clean every remaining surface of solids and residue, then apply a hospital-grade disinfectant and an antimicrobial, allowing the full label contact time.
Then the drying equipment goes in. Fast, complete drying is what limits mold growth afterward. Air movers and LGR dehumidifiers run until moisture readings on the slab, the framing and the base plates meet dry standard, which for a Chicago basement is usually 5 to 10 days. Before rebuild we do a final check for moisture, visible residue and odor. Odor that lingers after disinfection usually means something wet is still hiding behind a wall or under a built-in.
What to do before we arrive
- Stay out of the water. Do not enter the basement while there is standing water and the power is on.
- Cut the breaker for the basement if the panel is dry and reachable without stepping in water. Otherwise wait.
- Stop using water upstairs. Every flush and load of laundry adds to what is coming up the drain.
- Photograph from the stairs. Water line, the drain it came from, and anything stored on the floor. Do not move things yet.
- Report it to Chicago 311 or your suburb’s public works line, and do not run the furnace fan or a household vacuum.
Our guide on what to do and what not to touch after a sewage backup walks through the first hour.
Backwater valves and overhead sewers
Cleanup solves this backup. Two plumbing fixes address the next one.
A backwater valve (check valve) is installed on the sewer lateral where it leaves the house. When the street sewer surcharges, a flap closes and stops the flow back into the basement. It is the less expensive option, though it needs periodic cleaning.
An overhead sewer conversion disconnects the basement plumbing from the gravity sewer and reroutes it through an ejector pump that lifts waste to a line exiting above the likely flood level. It is the more thorough fix and the standard recommendation for finished basements and garden units.
Both require a licensed plumber and a permit. The City of Chicago and many suburbs run rebate programs for this work. Our summer storm checklist covers the prevention side in more detail.
Sewer backup and Illinois insurance
A standard Illinois homeowners policy (HO-3) covers sudden and accidental discharge from plumbing inside the house. It excludes sewer backup and sump pump overflow unless you added a water backup and sump discharge or overflow endorsement. Typical limits are $5,000 to $25,000, sometimes more, which is why a finished basement can exceed the limit.
Sewer backup is also a different peril from surface flooding. If water came over the sill from the yard or a river, that is flood, and it needs a separate NFIP or private flood policy. Our post on sewer backup versus flood claims explains how adjusters draw that line.
What the adjuster expects from us: dated photos of the water line and the drain it came from, a moisture map, a daily drying log, and an itemized scope of what was removed and why, usually in Xactimate format. We provide all of it and can bill the carrier directly where they approve.
Remove or keep after a Category 3 backup
| Material | Usually removed | Usually cleaned and kept |
|---|---|---|
| Carpet and pad | Always | Never |
| Drywall below the water line | Always, cut above the wet edge | Only above the cut line |
| Wood framing and studs | Rarely | Yes, once exposed, cleaned and dried |
| Concrete slab and block walls | Never | Always, scrubbed and disinfected |
| Particleboard cabinets and trim | Always | No |
| Metal shelving, tools, sealed bins | No | Yes |
| Boxes, books, paper, mattresses | Always | No |
What drives the cost of sewage cleanup in Chicago
Sewage backup cleanup and sanitization typically runs $3,000 to $10,000. Where a finished basement with a bathroom, bedroom and living area is involved, full restoration for gray or black water runs $6,500 to $18,000 or more. The emergency call-out and inspection is $250 to $500 and is credited against the restoration work.
The main cost drivers are:
- How much of the basement is finished. Bare concrete cleans up fast; drywall, carpet and built-ins have to come out.
- Contents. A basement used for storage means more disposal and a longer contents inventory.
- Drying time. Basements run 5 to 10 days on equipment at $50 to $125 per unit per day.
Sewage cleanup is often the first phase of a larger basement flooding cleanup, and a basement that sat wet for days may need mold remediation after it. If water is coming up through your floor drain right now, stay upstairs and call us or send the form.
Last updated September 15, 2026
