Flooded basement cleanup, beginning with safety

If the soil outside is still saturated, pumping a basement dry too quickly can leave pressure against the walls. With a large flood, ask the contractor or local officials before removing it all at once. Smaller water from a pipe or an appliance is more straightforward.

Dark or foul water suggests a sewer problem, which is a different job. See sewage backup cleanup. Clean water can go straight to water extraction.

Concrete and block can usually be cleaned and dried. Carpet, pad, soaked insulation and drywall often come out, especially after floodwater. Furnaces, water heaters and panels that got wet should be checked by a qualified technician before use.

Stored items are a separate decision. Photograph them before discarding anything, since those photos support an insurance claim.

A failed sump pump usually means water near the pit and along the floor edge. Seepage shows up at the joint between wall and floor or through cracks. A clean, fast flood often points to a supply line or water heater. Dark water coming from a floor drain suggests a sewer backup, especially during heavy rain.

Knowing the cause also decides who pays, since insurers treat these events differently. Note what you saw first, and take a photo if you can do so safely.

Damp basements can send humid air upstairs. Keep a dehumidifier running until readings return to normal, and clean surfaces that floodwater touched. If there are fuel tanks or chemicals in the basement, be alert to spills and odors, and call the fire department if you smell fuel or gas. Mold guidance is on our prevention page.

Most people want to know three things: is it safe to go down, where did the water come from, and what can be saved? Safety depends on the power and fuel systems. Source shows in the pattern: pit overflow suggests the sump, wet wall joints suggest seepage, and a dirty floor drain suggests the sewer.

Finished basements call for more tear-out than unfinished ones, because carpet, paneling and drywall trap water against concrete.

Read why sump pumps fail and water damage categories explained.

During a regional flood, the soil around the house may hold as much water as the basement does. That water pushes on the walls from outside, while the water inside pushes back. Draining the room quickly takes away that balance, and block or poured walls can crack, bow or even collapse.

A common rule of thumb is to wait until water outside has gone down, then lower the level inside gradually, in steps, watching for water to rise again overnight. If the level comes back up after pumping, the ground is still saturated and the pump is losing the race. The contractor can judge timing based on what they see, and local officials may have advice during a wide flood.

This caution matters most with deep water from outside. A failed water heater or a broken supply line leaves no such pressure in the soil, so that water can normally be removed right away.

River and storm water leave a layer of mud that can look harmless once dry. CDC warns that floodwater can carry bacteria from sewage and agricultural or industrial waste, so wear rubber boots, gloves and goggles while dealing with it. Shovel out the mud while it is still wet, since dry silt becomes dust and is harder to shift. Then clean walls and floors with hot water and detergent.

Do not wash mud down a floor drain in bulk, because it can settle and plug the line. Avoid the temptation to run a gas-powered pressure washer indoors. CDC says never to run such equipment inside a home, basement or garage because of carbon monoxide, and that includes keeping it away from open windows or vents. Generators belong outdoors as well, at least 20 feet from any openings.

After pumping, take a look at the floor drain, the sump pit and any cleanout. A drain that gurgles or a pit that refills quickly tells you the source has not gone away. Tell the contractor about any rise in level, and mark the waterline with tape so you can compare it over a few hours.

Check outside too. Gutters that dump at the foundation, a window well full of leaves and ground that slopes back toward the house all feed water into the same spots. On many houses, the simplest fix is also among the most useful: moving water away from the foundation at the surface.

If walls and floors were lost, consider using materials that tolerate water. Tile and sealed concrete recover far better than carpet. Cement board and other moisture-resistant panels hold up better low on a wall than ordinary paper-faced drywall, and leaving a small gap at the floor can help keep wall material out of a shallow puddle. Raised storage and shelving keep belongings clear of the floor.

Do not close anything up until the concrete and framing have reached their target readings. Moisture stays in masonry for a long time, and a new wall built too soon can start growing mold from behind. Mechanical equipment can sometimes be raised onto a platform, or moved higher in the house, but that is a discussion for your HVAC contractor and local code officials. Basements used for sleeping also have egress requirements, so ask about them before rebuilding a bedroom.

Standard homeowners policies commonly exclude surface flooding, and a separate flood policy may be limited in what it pays for below grade, so read the basement section with care. Sewer and sump overflow is usually covered, if at all, by an add-on. A broken pipe inside the house is often handled in another way entirely. This is why the insurer will ask where the water came from, and why you want to note it before the evidence is cleaned up.

Describe what you saw in plain terms and leave the labeling to the adjuster. Photos of the sump, the drain and the outside ground are useful here, and a plumber's note on the cause carries weight. Working with your adjuster has more detail on preparing for the visit.

Ready.gov's flood page tells anyone with a lung condition or a compromised immune system to avoid a leaking or visibly moldy building, and it keeps children out of cleanup work too. Pets belong elsewhere too, since paws carry contaminated silt upstairs.

Close the basement door when you can, and consider laying down a boot-off zone at the top of the steps so that dirty water does not get tracked through the house. Wash with soap and water after any contact. CDC says to wash open cuts or sores that are exposed to floodwater and to get medical attention right away if you are hurt or become sick.

Basement air tends to rise into the house, carrying damp and smell. Keep the door shut when the crew allows it, and check whether the furnace return draws air from the basement. If it does, ask the technician before you run the system. A closed-off basement with a dehumidifier usually protects upstairs rooms better than fans blowing air around the house.

Close off floor vents leading to wet areas if the contractor agrees. Once the floor and walls test dry, normal airflow can resume, and any lingering smell is a useful signal to investigate further.

Where you live changes flooded basement cleanup. See Oregon, Connecticut, Delaware, Kansas, Louisiana, New Hampshire, Chicago, Dallas, Colorado Springs, Cedar Hill, Lake Stevens, Norcross, Port Charlotte, Prosper, Atlanta, Indianapolis.

Go straight to the first steps: emergency flooded basement services.