A flooded basement with sewage in it. Stay out of the water
Standing water near electrical panels, outlets and appliances can be live, and sewage in it makes this Category 3 water that has to be removed and the space disinfected.
What is probably happening
- Sewage backs up through the lowest drain in the house, which is usually a basement floor drain or shower. Heavy rain, a blocked main line or a failed sump can all cause it.
- Everything the water touched that is porous is a loss: carpet, padding, drywall that went soft, cardboard, upholstered furniture, mattresses.
- The crew pumps out, removes contaminated material, disinfects hard surfaces, and dries with dehumidifiers and air movers over days.
Do this in the next five minutes
- Keep everyone, especially children and pets, upstairs.
- If power can be cut safely from a dry location, cut it to the basement. If the panel is in the wet area, call the utility.
- Stop using water in the house.
- Photograph from the top of the stairs.
- Call your insurer, then a plumber for the cause and a Category 3 restoration company for the cleanup.
- If you must enter later with the crew, wear rubber boots, rubber gloves and goggles, and wash with soap and water afterwards.
Do not
- Do not wade in to rescue belongings while the power is on. Water and electricity kill.
- Do not use a household wet vac and dump it down the same drain.
- Do not leave it for the weekend. Wet wood, drywall and carpet can start growing mold after 24 hours.
Who to call
A water damage restoration company that handles Category 3 water
This is a sewage-contaminated water loss under IICRC S500; the restoration firm extracts, removes and dries, while the plumber only fixes what caused it.
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What it should cost
$7,000 to $15,000 for black water
Angi flooded basement cleanup by water type; clean water runs $1,500 to $3,500 and the overall average is $4,000
Source: Angi, flooded basement cleanup cost, May 2026. View source
National published range, not a quote for your job. The full cost table for this trade is on the water damage page.
Ask this contractor, on the phone, before anyone comes out
Tap each one as you ask it.
- Is this being treated as Category 3 water under S500, and is that written in the scope?
- What is being removed and disposed of, and where does the waste go?
- How many days of drying, and will you leave daily moisture readings?
- Are you asking me to sign an Assignment of Benefits?
- Is the plumbing repair or sump pump replacement part of this quote?
End the call if
- A plan to dry carpet and padding in place after sewage exposure.
- An Assignment of Benefits or a large deposit demanded on the first visit.
- No written scope naming the water category.