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After a basement flood

Basement Flooded? What to Do in the First Hour (and the Next 48)

In the first hour after a basement floods, stay out of water near outlets or the electrical panel, shut off power and gas only from dry ground, stop the source, and photograph everything before you move anything. Then call your insurer, remove the water, and get wet carpet pad, insulation and drywall drying or out within 24–48 hours.

The First 48 HoursDIY or Call a Pro?

Safety first (CDC)

Before you step down

  • Don't enter water that could reach outlets, cords, appliances or the panel.
  • Turn power off only from a dry spot; otherwise call an electrician or the utility.
  • Smell gas? Leave now and call the gas company or 911 from outside.
  • Never run a generator or gas pump indoors; keep it at least 20 feet from doors and windows.

Don't turn on a furnace or air handler that was underwater until a technician checks it.

Water still rising? What to do while the sump pump is down comes first. This page starts once the water has stopped rising.

Step by step

The first 48 hours, step by step

Every list of flood steps says the same things. What matters is when: the first hour is about safety and evidence, and the next 48 are a race against mold.

  1. 0–15 minutes: make it safe. Stay out of any water that could reach electricity. Switch the basement circuits off from the panel only if you can reach it from dry floor; if not, call an electrician or the utility. Gas smell means leave. If water is still coming in, the sump-failure guide has the stopgaps.
  2. 15–60 minutes: stop the source, then document. For a burst pipe or appliance, close the main water shutoff. For groundwater or a storm there is nothing to shut; move on. Before you lift a single box, work through the shot list below.
  3. 1–24 hours: call, extract, open up. Call the insurer and note the claim number. Pump out anything deeper than about an inch, then finish with a wet/dry vac on a GFCI outlet. Get wet boxes, rugs and carpet pad out of the basement. Open interior doors and run fans only once you know the water was clean (EPA).
  4. 24–48 hours: the drying window. This is EPA's window for drying water-damaged materials before mold growth. Run a dehumidifier and fans continuously, aiming for 30–50% relative humidity. Anything that isn't drying by day two (swollen drywall, wet insulation, upholstery) gets removed.
  5. 48 hours and later: assume mold. CDC advises treating anything not yet dry as moldy. Clean water that has stood this long is treated as Category 2 under the IICRC S500, so wear goggles and an N95 and discard more.
The flood clock: what to do after a basement floods, by timeA vertical timeline in five bands. 0 to 15 minutes: make it safe; turn power off only from dry ground, leave and call the utility for a gas smell, and go to the sump pump failure guide if water is still rising. 15 to 60 minutes: close the main water valve, then take photos and video before moving anything. 1 to 24 hours: call the insurer, pump and vacuum the water, and pull out carpet pad and wet boxes. 24 to 48 hours: the drying window; run a dehumidifier and fans to 30 to 50 percent humidity, cut out anything not drying, and check the base of the drywall with a meter. After 48 hours: assume mold on anything still wet, and clean water is now treated as Category 2. A bracket marks 24 to 48 hours as the mold window. Sources: CDC, EPA, IICRC S500.The flood clock0–15 minMake it safePower off from dry ground onlyGas smell: leave, call utilityStill rising? Sump-failed guide15–60 minStop it, then record itClose the main water valvePhotos and video beforeyou move anything1–24 hCall, extract, open upCall the insurerPump, then wet/dry vacPull pad and wet boxes out24–48 hThe drying windowDehumidifier + fans, 30–50% RHNot drying? Cut it outMeter the drywall base48 h +Assume moldTreat anything still wet as moldyClean water now countsas Category 2moldwindowCat 1 →Cat 2
The flood clock. Time bands from CDC re-entry guidance, EPA's 24–48 hour drying window, and the IICRC S500 time-and-temperature rule for water categories.

Water category

What kind of water is it?

Where it came fromCategoryProtectionWhat can be keptDefaultWhich policy may pay
Supply line, water heater (clean)1Gloves, bootsCarpet can often be dried; pad usually goesDIY if smallHomeowners policy, often
Washer, dishwasher, toilet without feces2Add goggles, N95Pad, wet insulation, swollen drywall goDIY with cautionHomeowners policy, often
Sump overflow, groundwater or rain seepage2Add goggles, N95Pad goes; carpet usually goesDIY with cautionBackup endorsement, or none
Sewage, floor-drain backup3Full PPE; keep kids and pets outPorous materials discardedProBackup endorsement
Outside floodwater3Full PPEPorous materials discardedProFlood policy

Categories from the IICRC S500 standard; keep/discard from EPA Table 1. Insurance column is how standard U.S. policies are typically written, not a coverage decision.

Rain or groundwater that seeped through the wall or slab is generally treated as Category 2, not clean water, so the carpet pad goes. To apply the rules to your own basement, check whether you can clean this up yourself.

Before you clean

Document it before you clean: the shot list

Take thisWhy the adjuster wants it
A wide shot of each wall and the whole floor, from the stairsShows the extent before anything moves.
The high-water line with a tape measure in the frameDepth decides what was reachable and how much is claimed.
The source close-up: the failed supply line, the sump pit and float, the floor drain, or the entry pointCoverage turns on cause; this is the first thing an adjuster asks.
Data plates (make, model, serial) on the furnace, water heater, washer, dryer, freezer and sump pumpFEMA and state flood guides tell policyholders to record these for appliances.
A date-stamped video walk-through, saying out loud when the water startedFixes the timeline in one file.
A cut sample of carpet and pad, plus receipts for pumps, fans and dehumidifier rentalProves the material grade after it's thrown out; mitigation costs are often claimable.

Then call the insurer, early, even if you are not sure you are covered. Coverage depends on how the water got in; see what homeowners insurance usually covers, by cause.

Materials

What to keep, dry, or throw out

MaterialWhat to do
Concrete wall and slabExtract the water; dry with dehumidifiers, fans or heaters.
CarpetExtract with a wet vacuum and dry within 24–48 hours (clean water only).
Carpet padDiscard; it holds water and rarely dries in time.
DrywallDry in place only if it isn't swollen and the seams are intact. Otherwise remove and replace.
Fiberglass or cellulose insulationDiscard and replace.
Ceiling tileDiscard and replace.
Vinyl, tile, hard flooringClean and dry; check the underlayment underneath.
Upholstered furnitureExtract and dry; it may not dry within 48 hours.
Boxes, books, paperDiscard what isn't valuable; freeze valuable papers.

EPA, Mold Remediation in Schools and Commercial Buildings, Table 1 (response within 24–48 hours). EPA's table assumes clean water; for sewage or contaminated water it calls for protective equipment and professional help.

Keep, dry or cut out: a finished basement wall after a floodCross-section of a finished basement wall and floor after a flood, with the water line marked. Concrete wall and slab: extract the water and dry. Drywall: dry in place only if it isn't swollen and the seams are intact, otherwise remove and replace. Fiberglass insulation in the wall: discard. Carpet: extract and dry within 24 to 48 hours if the water was clean. Carpet pad: discard. Water wicks up drywall above the water line, so check above it. Labels follow EPA Table 1.water lineConcrete wall and slabExtract water, then dryInsulationDiscard and replaceDrywallDry in place only if notswollen, seams intact;otherwise cut outWicking zoneCheck above the water lineCarpet: extract and dry(clean water, 24–48 h)Pad: discard
Keep, dry or cut out, following EPA Table 1. Water wicks up drywall above the water line, so check above it before deciding where to cut. We don't give a fixed flood-cut height: it depends on what your meter reads.

Drying

Drying: how to know it's actually dry

A dry-looking floor isn't dry. Run a dehumidifier sized for the space (size a dehumidifier for the space) and two or three fans nonstop, doors closed to the rest of the house, emptying or draining the bucket constantly. Aim for the humidity to aim for, 30–50%. Check the bottom of the drywall and the framing with a pin moisture meter and compare with a dry wall upstairs. Don't close walls or lay new flooring until the readings match.

Getting help

When to call a water mitigation company

  • Sewage, a floor-drain backup, or outside floodwater (Category 3).
  • More than about 100 sq ft wet, or an inch or more across the floor.
  • Wet insulation behind drywall, or anything still wet at 48 hours.
  • Visible mold over about 10 sq ft (EPA).
  • Someone in the home with asthma, a weakened immune system, or an infant (CDC).
DIY or Call a Pro?

Mistakes

Mistakes that make it worse

Afterwards

After it's dry: stop it happening again

Once the basement is dry, work out why it flooded: read why basements flood and how to prevent a repeat, and narrow down where the water got in. If a contractor proposes a system, check a waterproofing quote before you sign, or request an inspection.

Written by the Wet Basement Fixes editorial team, reviewed against CDC, EPA, IICRC and FEMA sources under our editorial policy. Last reviewed: October 18, 2026.

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FAQs

Basement flooded: common questions

What is the first thing to do when a basement floods?

Make it safe. Don't step into water that could reach outlets, cords or the panel. Turn the power off only from a dry spot, or call an electrician or the utility. If you smell gas, leave the house and call the gas company from outside. Then stop the source and take photos.

Is it safe to stay in the house with a flooded basement?

Usually yes, upstairs, if power to the basement is off, there's no gas smell, no generator or gas pump is running indoors, and the water isn't sewage. If any of those aren't true, CDC guidance points to staying out until the hazard is dealt with.

How long does a flooded basement take to dry?

Aim to have materials dry within 24–48 hours, EPA's window for preventing mold. Concrete and wood framing can take days to weeks longer. Don't judge by touch: confirm with a moisture meter, comparing wet areas with a dry part of the house, before closing up walls.

How soon does mold grow after a basement flood?

EPA and CDC both use 24–48 hours: if wet materials aren't dry by then, assume mold has started. It may not be visible for days. Anything porous that stayed wet longer, such as pad, insulation or swollen drywall, is usually removed rather than dried.

Should I call my insurance company before cleaning up?

Make it safe and stop further damage first, then document, then call early. Most policies expect prompt notice and reasonable steps to prevent more damage, so pumping and drying usually shouldn't wait. Photograph everything and keep removed samples and receipts. This is general information, not coverage advice.

Can I clean a flooded basement myself?

Often, if the water was clean, shallow and limited to a small area, nothing electrical is involved, and it can be dry within 24–48 hours. Sewage, outside floodwater, wet insulation behind drywall, large wet areas, or vulnerable people in the house point to a water mitigation company.

Sources

Sources