Sewage Backing Up Into Your Basement? What to Do Next

Sewage rising through a basement floor drain means wastewater cannot get past a blockage or an overloaded sewer. Stop using every sink, toilet and appliance, keep children and pets away, and report it: Baltimore City residents call 311 and Baltimore County residents call 410-887-7415. Rain-related backups in the City can qualify for free DPW cleanup or up to $5,000 in reimbursement.

Call (716) 328-9097

Sewage near outlets or the electrical panel? Stay out of the water.

Do this first

Stop using all sinks, toilets and appliances.
Keep children and pets away from the sewage.
Cut power only from a dry spot.
Report it: 311 in the City, 410-887-7415 in the County.
Photograph everything before cleanup.
Keep every cleanup receipt.

Step 1 of 7

Stop using water and every drain in the house

Stop using sinks, showers, toilets, dishwashers and washing machines immediately. Baltimore County’s public works department explains why: when water cannot get through the house connection lateral to the main sewer, it backs up into the house, and every gallon you drain adds to it.

Step 2 of 7

Keep children and pets away from the sewage

CDC and Baltimore City DPW both say to keep children and pets away from the affected area until cleanup is complete. EPA adds that children and pregnant people should not take part in flood cleanup.

Step 3 of 7

Deal with electricity from a dry spot

DPW’s backup brochure tells residents to turn off the power immediately when there is standing water or wiring near the backup. CDC adds the safety limit that matters:

Never step into standing water to reach the panel. CDC says to call an electrician when reaching the main breaker means entering standing water, and never to switch power on or off while standing in water.

Step 4 of 7

Report the backup

Baltimore City: call 311, or (443) 263-2220 from outside the city. For a sewer overflow, DPW sends staff to investigate, clean and repair. A 311 report made as soon as the backup is found is required for the free cleanup program described below.
Baltimore County: call 410-887-7415, or 410-887-5210 after hours. County crews clear stoppages in the public portion of the lateral through a visible cleanout on the property, and mop basements after a sewer main overflow.

Step 5 of 7

Photograph the damage and keep every receipt

DPW’s reimbursement program requires documentation of all cleanup, disinfection and disposal costs, including any insurance deductible, and tenants must include a lease signed by the owner. Photograph the water line on walls, the drain it came from and every damaged item before anything is thrown out.

Step 6 of 7

Clean up in protective gear, or hire certified pros

Wear rubber boots, rubber gloves and goggles (CDC), plus an N-95 respirator, long sleeves and pants (EPA).
Throw away what cannot be cleaned or dried quickly: carpet and padding, rugs, mattresses, upholstered furniture, stuffed toys, books and paper (CDC).
Remove drywall and insulation that sewage reached (CDC).
Clean surfaces with hot water and detergent before any disinfectant, and never mix bleach with ammonia or other chemicals (EPA).
Hire a cleanup firm certified by the Institute of Inspection, Cleaning and Restoration Certification (IICRC) for large jobs; DPW recommends getting at least three estimates first.

Step 7 of 7

Get the blockage or broken lateral on your side fixed

In Baltimore City, DPW maintains the sewer lateral from the main to the property line, and the owner is responsible for the sewer pipe within the property line. DPW calls repairing a broken lateral the homeowner’s responsibility. When the problem is in the house connection and there is no exterior cleanout, DPW says you must hire a licensed plumber. Repair options and permits are covered on our Baltimore sewer line repair page.

What causes a basement sewage backup?

Baltimore City DPW names two causes: blocked or failed pipes, and rain or groundwater overloading the sewer. Blockages come from grease, wipes and sanitary products, tree roots and deteriorating pipe; wet-weather flows enter through cracks, loose joints and illegal connections.

DPW’s cleanup program FAQ says most City backups happen in dry weather, typically from an existing blockage. Baltimore County reports that roots, debris and grease cause more than 70% of its manhole overflows. DPW’s rule of thumb for a wet-weather event is light rain for 2 to 3 hours, moderate rain for 30 to 60 minutes, or heavy rain for 15 minutes.

Will Baltimore City pay to clean up a sewage backup?

Only for backups caused by rain overloading the public sewer. DPW offers free professional cleanup through its Sewage Onsite Support (SOS) program, or reimbursement of up to $5,000 through its Expedited Reimbursement Program, and a household can use one or the other for a backup, not both.

Baltimore City DPW sewage backup programs
Detail	Sewage Onsite Support (SOS)	Expedited Reimbursement Program
What you get	Free cleaning and disinfection; removal of soiled carpet, flooring and furniture; deodorizing and drying	Up to $5,000 per dwelling unit, per event, for documented cleanup, disinfection and disposal
Which backups	Capacity-related wet-weather backups the City confirms; not clogs from wipes, roots or grease, and not water main breaks	At least ¼ inch of rain within 24 hours that surcharged the sewer; backups on or after April 6, 2018
Who qualifies	Residential owners, tenants or property managers	City residential customers, homeowners or tenants; insured owners need their insurer’s decision first
How to start	Call 311 as soon as the backup is found; a DPW inspector determines the cause	Apply within 90 days; call 410-396-3500 for a mailed application
Timing	The contractor calls within about an hour of notice; appointments 8 a.m. to midnight, seven days a week	Decisions within 60 days of a complete application

Approval is not common: Baltimore Brew reported 39 reimbursement applications and 3 approvals in fiscal 2024, against 4,648 backups DPW counted in 2023. Property damage is excluded from the reimbursement program; DPW directs those losses, and dry-weather backups, to a claim with the City Law Department. In 2023, EPA and the Maryland Department of the Environment ordered the City to extend cleanup help to backups caused by City pipes in any weather, and Baltimore Brew reported in February 2026 that DPW had not yet complied.

Does homeowners insurance cover a sewage backup?

Not a typical policy. The Insurance Information Institute says sewer backup is excluded from standard homeowners and flood insurance and has to be bought as a separate product or an endorsement.

The Maryland Insurance Administration notes that Maryland law requires insurers to offer that coverage for an additional premium, and that most such policies pay for the damage from the backed-up water but not for repairing or replacing the pipe itself.

Preventing the next backup

Keep grease, wipes, diapers and paper towels out of drains; DPW lists them among the main causes of clogs.
Have a licensed plumber install an exterior cleanout, which DPW recommends so the lateral can be reached at ground level.
Consider a backwater valve, which the Insurance Information Institute describes as letting sewage flow out but not back in; DPW suggests considering a backflow preventer.
Ask your insurer about a sewer backup rider, as DPW advises.

What a lateral repair or replacement typically costs, dig versus trenchless, is in the sewer line replacement cost guide.

Sewage backup questions

Who do I call when sewage backs up into my basement in Baltimore?

In Baltimore City, call 311, or (443) 263-2220 from outside the city. In Baltimore County, call 410-887-7415, or 410-887-5210 after hours. A blockage in the private lateral inside your property line needs a licensed plumber.

Will Baltimore City pay for my sewage backup cleanup?

Only for backups caused by rain overloading the public sewer. DPW’s SOS program provides free cleanup if you call 311 right away, or its reimbursement program pays up to $5,000 if you apply within 90 days. Dry-weather clogs are not covered.

Is a sewage backup covered by homeowners insurance?

Not under a typical policy, according to the Insurance Information Institute. Maryland law requires insurers to offer sewer backup coverage for an extra premium, and most of those policies still exclude repairing the pipe itself.

Who is responsible for the sewer line in Baltimore City?

DPW maintains the sewer lateral from the main to the property line. The property owner is responsible for the sewer pipe inside the building and within the property line, including repairing a broken lateral on that side.

When the problem is your sewer lateral

Repeated backups from a root-filled, cracked or collapsed lateral end only when the line itself is repaired. See how that work is done, and what it costs, on our sewer lateral repair service for Baltimore homes page.

Sources

Checked 2026-09-13. Plumbing and safety guidance changes; follow your utility’s and insurer’s current instructions.

Sewage coming up the drain?

Report it to 311 or the County, then call Speedy Plumbing Baltimore for the private-side repair. The line is answered 24 hours a day.

Call (716) 328-9097