How do I dry out a wet basement after a leak?

A wet basement can usually be dried out by you if the water was clean, came from a single leak, and you start within a day. The order is: make it safe, stop the source, get the water and the soaked materials out, then move air and pull moisture out of it until the humidity drops. The clock matters: it is important to dry water-damaged areas and items within 24-48 hours to prevent mold growth.^[2]

Make it safe first

Basements and electricity are a bad mix. Do not touch electrical equipment if it is wet or if you are standing in water.^[1] Turn off the electricity to prevent electric shock if it is safe to do so.^[1] If reaching the panel means standing in water, do not go in. Call an electrician or your utility instead.

If the water came from the outside, a sewer line or a backup, stop here and read the pro section below. Clean water from a broken supply pipe or a leaking water heater is the case this guide is for.

Stop the source, then document

Shut off the water to whatever is leaking. Then, before you move anything, take photographs to show the way things look before you begin cleaning and repairing, and be sure to keep receipts for all of your clean-up expenses.^[4] Your insurer may want to see items you think are a total loss, so set those aside instead of putting them at the curb.

Get the water and the wet materials out

Remove standing water first. A wet-dry vacuum handles an inch or two; deeper water needs a pump. If you run a gasoline pump or generator, remember to use a generator or other gasoline-powered machinery ONLY outdoors and away from windows.^[1] Run the hose or cord through a door or window, never with the engine in the basement.

Then take out what will not dry. Carpet and padding are the usual casualties: absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they become moldy.^[3] Lift them early, because the underside stays wet long after the top feels dry. Move furniture, boxes and cardboard storage off the floor, since cardboard and particleboard soak up moisture and rarely recover.

Dry the space

Open the windows when the air outside is drier than the air inside, and set fans so they blow across wet floors and the lower part of the walls. Close the windows and run a dehumidifier when the outdoor air is damp. In a closed basement, a dehumidifier does the real work of removing moisture, and fans help it by keeping air moving over wet surfaces. Empty the tank often, or run the drain hose to a floor drain or sink.

Check your progress with numbers. If possible, keep indoor humidity below 60 percent (ideally between 30 and 50 percent) relative humidity.^[2] A basement that still reads high after several days is holding water somewhere, in the slab, in the drywall or in the insulation behind it.

If you got to it quickly, you are in the good case: if wet or damp materials or areas are dried 24-48 hours after a leak or spill happens, in most cases mold will not grow.^[2]

Check what you cannot see

Drywall wicks water upward and traps it behind the paint. Press along the bottom of the walls, check baseboards, and sniff for a musty smell. If wall cavities stay wet, have a pro open the wall and measure it, since wiring and pipes run behind drywall and wet insulation has to come out so the cavity can dry. If you believe that you may have a hidden mold problem, consider hiring an experienced professional.^[2]

Stop and call a pro if

• The water was sewage or otherwise contaminated. If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who has experience cleaning and fixing buildings damaged by contaminated water.^[3]
• Water is touching outlets, the panel, or a furnace or water heater, or you cannot safely reach the breakers.
• A lot of walls, ceilings or floors are soaked, or mold covers a large area. If there has been a lot of water damage, and/or mold growth covers more than 10 square feet, consult EPA's Mold Remediation in Schools and Commercial Buildings.^[2]
• The basement is not drying after several days, or the humidity will not come down.
• A household member has asthma or a weakened immune system. People with asthma and other lung conditions and/or immune suppression should not enter buildings with indoor water leaks or mold growth that can be seen or smelled.^[1]

Getting help in Virginia

If you are unsure whether this is a DIY job, read when you need a pro to dry out a house after a leak, and what professional water extraction and drying costs in Virginia. For the first hour, see what to do first after water damage. Browse restoration services or more restoration answers.

When you want a restoration company to take over, describe the damage once and licensed local businesses quote it.