After a storm, sewage that rises through a floor drain or a basement fixture should be treated as a health hazard. Stop using every fixture on the line, keep people and pets out of the room, photograph the water and call a crew, since sewage removal and disinfection need protective equipment and a plan for every surface.
Key takeaways
- Stop using every fixture on the line the moment water appears in a drain, a laundry tub or a basement toilet.
- Keep people and pets out of the affected room, because sewage can carry illness.
- Photograph the water, the drain and the water line before anything is cleaned or moved.
- Call a crew for removal and disinfection, and a plumber for the blocked or overloaded line.
- Do not run a sump pump or a household vacuum in sewage, and do not treat the water as clean.
- Keep the readings, the photographs and the invoices, since a sewer backup is handled under different policy terms from many other water events.
Why does sewage come up a drain during a storm?
Sewage rises through a drain during a storm when the line cannot carry its flow, usually because the pipe is blocked or the system is full. The lowest drain in a house is the first place the water appears, which is why a basement floor drain often shows the problem first.
A drain carries waste by gravity, so any restriction in the line makes the water back up. Roots, grease, debris and a collapsed section can all restrict the flow, and a storm adds water to a line that may already be partly blocked. The water then has nowhere to go but up.
The city's material on Onondaga Creek describes the creek section as engineered for combined sewage and storm flows. In a system that carries both, heavy rain can fill the pipes and push water back toward the buildings at the bottom of the line. That is one reason a backup can start during a storm even when no fixture in the house is blocked.
What should you do in the first ten minutes?
In the first ten minutes, stop the water from getting worse by not using any fixture, keeping people away from the room and closing the door. Then call for help and start recording what you see, since the first steps are the ones that limit the harm.
Stop the washer, the dishwasher, the shower, the sink and the toilet. Each use adds water to the line and to the room. If the water is still rising, shut the main water valve if you can reach it from dry ground, since that stops more water from entering the system.
Close the door to the affected room, and keep children and pets out. Do not try to clear the drain with a plunger in a way that splashes the water, and do not reach into the water with bare skin. Once the room is secured, call the crew and a plumber, and note the time the water was first seen.
- Stop every fixture on the line, including the washer and dishwasher
- Close the main valve if it can be reached from dry ground
- Close the door and keep people and pets out of the room
- Note the time, the drains affected and where the water is now
- Call a crew for the room and a plumber for the line
What should you photograph before anything is moved?
Photograph the water on the floor, the drain, the water line on the walls and any debris before anything is cleaned or moved. The photographs show the condition of the room when the water was found, which the insurer and the crew will both need.
Take wide photographs of the room, then close-ups of the drain, the water line and the debris. Use a reference object such as a door frame or a coin to show scale. Include the date and time on each photograph, and keep the original files rather than copies sent through a messaging app.
Mark the highest water line on the wall with a pencil and a date if it is safe to do so. The mark is a reference point for the crew's readings and for any later question about how high the water rose.
What does a crew do with sewage in a basement?
A crew removes the standing sewage with pumps and wet vacuums, takes out the solids and soaked material, cleans and disinfects the hard surfaces, and dries the structure to readings. Protective equipment is used for every step, and disposal follows the rules for contaminated material.
The technician wears gloves, eye protection and boots, and a respirator where the water is heavily contaminated. Solids and soaked paper are bagged and removed. Porous materials such as carpet, pad, the lower part of drywall and some insulation are removed where they have soaked up the sewage, since a cleaning cannot reach what is inside them.
Hard surfaces are cleaned with a detergent and then disinfected. The room is dried with air movers and a dehumidifier, and the readings are logged at each visit until the structure reaches a dry level.
| Material | Usual treatment | Why |
|---|---|---|
| Concrete floor and sealed hard surfaces | Cleaned and disinfected in place | The surface can be made safe without removal |
| Carpet and pad | Usually removed | Sewage soaks through the fibres and pad and cannot be cleaned to a safe level |
| Lower drywall | Cut back to the wet line and removed | The paper and core hold the sewage and cannot be dried in place |
| Wood framing and sill | Cleaned, disinfected and dried, replaced if soft | Sound wood can be treated, but soft or stained wood is replaced |
| Upholstered furniture and soft goods | Usually discarded | Sewage cannot be removed from porous soft material |
| Stored paper and books | Usually discarded | Paper holds the water and the contamination |
Can a sump pump be used in sewage?
A sump pump moves groundwater, not sewage, and it should not be used to pump sewage unless it is designed for that purpose. A sump basin that is taking in sewage should be turned off until a crew has checked the system.
A standard sump pump is built to move clean water and is not rated to handle the solids and the bacteria in sewage. Running it in sewage can damage the pump and spread the contamination through the discharge line, which is a bigger problem than the original backup.
If the sump is part of the problem, tell the crew and the plumber. The sump basin, the discharge line and the check valve may all need to be inspected before the pump is used again.
How do you stop a backup from happening again?
A backup can be reduced by keeping the drains clear, by avoiding fixture use during a storm and by having a plumber assess a backwater valve or a backup device. No method removes the risk entirely, but each lowers the chance of a repeat.
Keep grease, wipes and paper towels out of the drains, since they tangle in the line and collect other debris. Have the line checked by a plumber if backups have happened before, and ask whether roots or a collapsed section are involved.
A plumber can assess whether a backwater valve is suitable for a particular house. The valve sits on the sewer line and closes when the flow reverses. Whether a valve is needed depends on the house and the line, so ask a plumber for an assessment rather than relying on a general answer.
What should you tell the insurer about a sewer backup?
Tell the insurer the time the water was found, where it came up and what you saw. Many standard policies exclude sewer or drain backup unless a separate endorsement is held, so the policy wording is the first thing to read.
Ask the insurer to explain how it treats sewer and drain backup, and ask for the terms in writing. A backup endorsement, if one is held, may cover the event, and the policy's definitions decide what counts as a backup.
Keep the crew's note, the readings, the photographs, the plumber's report and the invoices. For a dispute about how the claim is handled, the New York State Department of Financial Services is the state regulator for insurers.
Who should do what after a sewer backup?
The crew handles the water, the sewage and the drying in the room. The plumber handles the line. The municipality or the owner handles the public or private sewer, depending on where the line runs, so the crew's note should say which system served the house.
A crew is not a plumber, and it does not clear a blocked line. Its job is to remove the sewage, clean and disinfect the surfaces, remove the soaked materials and dry the structure. The plumber's job is to find the blockage, clear it and check the line for damage, and the two should work from the same note.
The line's maintainer depends on where the blockage sits. A blockage in a private lateral is usually the owner's responsibility to clear, while a blockage in a public main is handled by the office that maintains it. The sourced material for this guide does not set out each case, so ask the city or the village office which system serves the house before the bill arrives.
- The crew removes sewage, cleans, disinfects and dries the room
- The plumber locates the blockage and clears the line
- The maintainer checks any public main that may be involved
- The owner keeps the note, the readings and the plumber's report together
What does a second backup tell you?
A second backup in the same place within a short time is a sign that the cause was not fixed. Ask the plumber to check the line and the drain for the cause, and ask the municipality whether the main has a known problem in the area.
If sewage returns to the same drain after the cleanup, the line has not been cleared or the cause has not been found. Call the plumber back before the room is closed up, since a second event can soak materials that were just dried and undo the work.
Keep a record of each backup with its date and time. A pattern of backups during heavy rain points to a problem in the system rather than a single blockage, and that pattern is useful evidence for the municipality and the insurer.
Frequently asked questions
Is sewage in the basement dangerous?
Yes. Sewage can carry bacteria and viruses, so keep people and pets out of the room and avoid contact with the water until it has been removed and disinfected.
Can I clear the drain myself?
A plunger can sometimes clear a fixture, but a plunger used on a floor drain can splash sewage. Call a plumber for the line, and keep the room closed until the crew has removed the water.
Will my insurer pay for a sewer backup?
That depends on the policy. Many standard policies exclude sewer and drain backup unless an endorsement is held, so read the terms and ask the insurer to confirm them in writing.
How long does the cleanup take?
It depends on the depth of the sewage and the materials affected. The crew explains the expected timing on site, and the drying continues until the readings show a dry structure.
What if the smell does not go away after the cleanup?
A lingering smell often means a wet cavity or porous material that was not removed. Call the crew back so the readings can be checked and the source found.
Sources
This guide is general information for Onondaga County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.