How to Handle a Sewer Backup in the First Hour

Why this matters

A sewer backup is dirty water coming up out of a drain instead of going down it, usually at the lowest drain in the house: a basement floor drain, a basement shower or toilet, a laundry tub. It is not just a mess. Sewage carries bacteria, viruses and parasites, it soaks into anything porous, and it often rises near the things that make water dangerous: outlets, extension cords, the furnace, the water heater, the electrical panel. What you do in the first hour decides how much more comes up, whether anyone gets hurt or sick, and how much of the damage your insurer can see and pay for.

Before anything else: if the water is touching or near outlets, cords, a power strip, baseboard heaters or appliances, or you cannot reach the electrical panel without standing in water, do not walk into it. Stay out of the room and call your electric utility or an electrician to cut power, and leave it off until an electrician has checked what got wet. If gas appliances such as a furnace or water heater are sitting in the water, do not touch them or try to relight anything; leave the room and call the gas utility.

Step 1: Stop all water going down any drain

The moment you see sewage coming up, tell everyone in the house: no flushing, no showers, no running taps, no dishwasher, no laundry. If the washing machine or dishwasher is mid-cycle, cancel it at the control panel (only if the machine is not standing in the water).

Why first: when the main sewer line out of the house is blocked, every gallon you send down any drain upstairs ends up at the lowest opening in the house, which is the one already overflowing. People keep flushing upstairs because those toilets "seem fine", and that is what turns an inch of water into three.

If you live in an attached home, a duplex or a condo that shares a sewer line, knock on your neighbors' doors and ask them to stop using water too. Their water may be what is coming up in your basement.

Step 2: Keep children and pets out, and protect yourself

Close the basement door or block the room. Children and pets will walk through it, touch things and put hands in mouths.

If you have to go near it at all (to photograph it from the doorway, or to lift something out that is not in the water), wear rubber boots and waterproof gloves, keep your hands away from your face, and wash with soap and water afterward. Anyone with a cut or open wound should stay out entirely. If anyone swallows sewage or gets it in a cut and then develops fever, vomiting or diarrhea over the next few days, see a doctor and tell them about the exposure.

Step 3: Air the space, but do not spread it

Open windows in the affected area if the weather allows, to let the smell and moisture out. If your furnace or air handler is in the flooded room, or its return grilles (the large grilles that pull air back into the system) are in that room, turn the heating and cooling system off at the thermostat so it does not pull the air through the rest of the house. Do not touch the equipment itself if it is in the water. Turn it back on once the area is cleaned and dry; if the water reached the equipment, it stays off until your heating contractor has checked it.

Do not mix cleaners to "kill the smell." Bleach mixed with products containing ammonia, or poured into urine-containing sewage, can release a gas that injures your lungs.

Step 4: Photograph before anything moves

Before anyone mops, lifts boxes or pulls up carpet, photograph and video it:

• A wide shot from the doorway showing the whole affected area.
• The water line: the highest point it reached on walls, furniture and boxes. A tape measure held against the wall in the shot shows the depth.
• The drain it came from, if you can see it from where you are standing.
• Damaged items, one shot per item or group, with any model labels for appliances that got wet.

Keep damaged items until your insurer tells you what to do with them. An adjuster who never saw the carpet has only your word for it.

See related: How to Photograph and Record a Problem for Your Contractor.

Step 5: Figure out which drains backed up, and when

This is the most useful thing you can tell a plumber, and it takes two minutes. Walk the house without running any water and note:

• Which drains have sewage in them, starting from the lowest level: floor drain, basement shower, basement toilet, laundry tub.
• Which drains upstairs behave oddly: a toilet that gurgles, a tub that drains slowly, water rising in a shower when a toilet is flushed.
• What was happening just before it started: a load of laundry draining, a bath, heavy rain, several people showering in the morning.
• Whether your neighbors have the same problem.

What that tells the plumber, roughly:

That table is a starting point for the conversation, not a diagnosis. The plumber confirms it with a camera or a drain machine.

Step 6: Call the right people

• If neighbors are backing up too, or it started in heavy rain, call your city or sewer district's line first. Many have a 24-hour number for sewer problems. Whether the problem is in your pipe or theirs decides who fixes it. See related: Whose Pipe Is It: What the Utility Owns and What You Own.
• Call a licensed plumber. Tell them it is an active sewer backup, which drains it is coming from, what you saw upstairs, and where your sewer cleanout is if you know (a capped pipe, usually 3 or 4 inches across, in the basement floor or wall or in the yard near the house). Do not open the cleanout cap yourself while the line is backed up; the sewage behind it is under pressure and comes out fast.
• Call your insurer, or at least open a claim online, within the hour if you can. Many standard homeowner policies exclude sewer backup unless you bought a sewer or water backup endorsement, so ask the question directly: "Do I have water backup coverage, and what do you need from me?" Write down the claim number.
• Call a water damage restoration company if the water covered more than a small area or soaked carpet or drywall. Your insurer may suggest one.

Why this is not a mop-and-bleach job

It is tempting to grab a mop, a bucket and the bleach and have it gone by lunch. Here is why that usually makes it worse.

Professional restorers classify water by how contaminated it is. ANSI/IICRC S500, the industry standard most restoration companies work to, puts sewage in Category 3, the most contaminated class. Under that standard, porous materials that sewage has soaked into, such as carpet and its pad, drywall below the water line, insulation, and particleboard furniture, are generally removed and thrown away rather than cleaned, because the contamination goes deeper than any surface cleaner reaches. Hard, non-porous surfaces like concrete, tile and metal can be cleaned and disinfected.

Bleach on a soaked carpet disinfects the top and leaves the pad underneath wet and contaminated, where it grows mold within days. Drywall wicks water upward past the visible line, so the wet zone is taller than it looks. A homeowner who mops and bleaches has often also removed the evidence the adjuster needed and left the part that causes the smell a month later.

A small backup on bare concrete, an inch or less that has not touched walls or belongings, is a different job: once the plumber has cleared the line, you can clean it yourself in boots and gloves with a household disinfectant used as its label directs. Anything bigger, or anything that touched drywall, carpet or wood, is a restorer's job.

A worked first hour

The house: a 1960s house with a finished basement. Carpet over most of the basement floor, a bare concrete laundry area of about 10 ft by 12 ft with a floor drain, and a basement shower.

9:40 a.m. The washing machine finishes its drain cycle. A minute later, water comes up the floor drain in the laundry area, gray and smelling of sewage. The shower drain next to it fills too.

9:42. One adult calls up the stairs: "Nobody flush, nobody run water." The washer is done, so there is nothing to cancel. The basement door is closed and the dog stays upstairs.

9:45. From the bottom stair, wearing rubber boots, they check: the water is spread across the concrete laundry area but has not reached the carpet edge, which is about 3 ft away. No outlets near the floor in that area; the washer is plugged in at about 4 ft up the wall. The furnace sits on a raised pad in the corner, dry. The power can stay on.

9:48. Photos: a wide shot from the stairs, a tape measure at the floor drain showing about half an inch of water, the shower drain, the carpet edge still dry.

That half inch over the 10 by 12 ft area is a useful number to give the plumber:

area   = 10 ft x 12 ft            = 120 sq ft
depth  = 0.5 in / 12 in per ft    = 0.0417 ft
volume = 120 sq ft x 0.0417 ft    = 5.0 cu ft
gallons= 5.0 cu ft x 7.48 gal/cu ft = about 37 gal
check  : 37 gal / 7.48 = 4.9 cu ft, / 120 = 0.041 ft

About 37 gallons is in the range of what one load of laundry sends down the drain, which fits the story: the washer drained into a line that had nowhere to go.

9:52. Walking upstairs without running water: the kitchen sink is empty, the upstairs toilet bowl looks normal. When someone tried flushing it before the warning, it gurgled. It has not rained in a week, and the neighbor on each side says their basements are dry. That points to the house's own main line rather than the city sewer.

9:58. Call to a licensed plumber: "Active sewer backup. Floor drain and basement shower came up right after the washer drained at 9:40. About half an inch over the laundry area, not on the carpet yet. Upstairs toilet gurgled when flushed. No rain, neighbors are fine. House is from the 1960s. Cleanout is a capped pipe in the basement wall behind the washer." The plumber says the age and the dry weather make roots in the line a likely suspect and books a drain cleaning and camera inspection for that afternoon.

10:15. Call to the insurer. The policy does have a water backup endorsement; the claim is opened and the adjuster asks for the photos and the plumber's invoice and camera findings.

10:30. Windows open, and the thermostat set to off, since the furnace shares the basement. Nobody uses water until the plumber clears the line. Because the water stayed on bare concrete, the family cleans the floor themselves after the line is cleared, in boots and gloves, with a disinfectant used as its label directs, and the heat goes back on once the floor is dry.

What would have changed the plan: if the water had reached the carpet, the carpet and pad would have been a restorer's removal, not a cleaning, and photographed in place first. If it had rained heavily overnight and the neighbors had wet basements too, the first call would have been to the city's sewer line, because a public main backing up into the house is a different repair with a different owner. And if the half inch had been three inches with the washer's outlet near the floor, the power to that area would have come off first, by the utility or an electrician, before anyone stepped down the stairs.

After the first hour

Once the line is cleared, ask the plumber what caused it (roots, a collapsed pipe, grease, a flushed wipe) and whether a camera inspection was done. Ask whether a backwater valve, a one-way valve that lets sewage flow out but closes when the public sewer pushes back, would help your house. That decision depends on how your plumbing is laid out and what your local code allows; see related: Backwater Valves and Sewer Backup. Put the invoice, the photos, the claim number and the cause in your house records. See related: Your House Records File and What Goes In It.

References

• ANSI/IICRC S500, Standard for Professional Water Damage Restoration (water categories and porous-material removal), as published by the IICRC; it binds restorers who work to it, not homeowners
• See related: Backwater Valves and Sewer Backup
• See related: The Drains in Your House and What Not to Put Down Them
• See related: Whose Pipe Is It: What the Utility Owns and What You Own
• See related: When to Stop and Call a Licensed Pro Around the House