5 Steps to Drying out a Flooded Basement

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Discovering the basement is wet, or worse flooded, can be a nightmare. Any volume of water can ruin carpeting, drywall and structural framing. Even if the basement is little more than a storage space, moisture condensation can buckle flooring and spawn harmful mold.

Basement flooding most often occurs from storms and melting snow. Even a small storm can trigger a deluge into the basement. An average sized home with a 1,500-square-foot roof sheds about 1,000 gallons of water for every inch of rainfall. Rising groundwater, which may be fed by an underground spring, can create flooding problems as well. Once water accumulates around a foundation, it can work its way inside through cracks joints, and porous materials.

1. Avoid dangers before pumping water out

  • Before pumping out a basement, inspect the ground outside the home. If there is deep standing water this can push against the outside of the home and in extreme cases fracture the exterior walls and cause them to collapse. It is important to wait until the water subsides before attempting to pump out the basement.
  • There are several cautionary items for flooded basements. Do not enter a flooded basement unless the electricity is off. Even several inches of standing water can transmit an electrical shock resulting in injury or death.
  • Take pictures of the flooded basement, for the insurance agency, before beginning repairs.
  • If the electrical power is off, use a gasoline-powered pump, but keep the pump outside and well away from the house to prevent carbon monoxide poising which can also be fatal.
  • Once it is safe to begin repairs, pump the water level down to 2 to 3-feet. Mark the water level and wait overnight. Check the water level the next day. If the water has risen, it is too soon to drain the basement. Wait 24 hours and pump the water level back down to 2 to 3-feet and wait overnight. If the water level has remained the same, it is now safe to pump the rest of the water out of the basement.

2. Remove mud and debris

  • Shovel out as much mud as possible. Mud left behind by floodwaters usually posses an extreme health hazard, so wear protective clothing and face coverings.
  • It is much easier to remove mud before it dries.
  • Hose off the basement walls and floors with clean water. Then disinfect all surfaces with a solution of 1-1/2 cups of liquid chlorine bleach to a gallon of fresh water. Never mix bleach and ammonia cleaning products! The combination of these two chemicals will create deadly chlorine gas.
  • Next, begin cleaning any heating and air conditioning systems. Remove all vents, registers, electrical covers and switch plates. Clean and disinfect them as above. Remember to leave the electrical power off for this step. All flexible ducting, which is nearly impossible to disinfect, should be replaced for health reasons.

3. Cleanup and dry out the basement

  • Open up basement windows and doors as much as possible to dry the structure and allow moist air to escape. Remove all wet furniture, contents and carpet, padding or rugs. Area rugs and carpet must be cleaned and disinfected before returning them to the basement. Replacing them is (unfortunately) the safest way to go.
  • Interior plaster walls should be inspected. If there was deep flooding, those walls will need to be drained if they are still holding water. Remove the baseboard trim and drill holes between the wall studs 2" above the floor to allow the water to escape. The holes can then be hidden behind the reinstalled baseboards. Flood soaked sections of wallboard will usually need to be removed above the waterline and thrown away. Prying out the bottom corners of the paneling and propping it out away from the wall studs until it dries can sometimes save paneled walls.
  • Disinfect all interior surfaces that were soaked by flooding with a commercial sanitizing solution or mix your own with ¼ cup of chlorine bleach mixed with one gallon of water. To remove mildew, use a commercial mildew remover or a fungicide. Remember: never mix bleach and ammonia cleaning products together. They will produce a deadly chlorine gas!

4. Restore the water system and electrical power

  • Carefully inspect all water systems including drains, vents and utility connections for leaks, broken pipes and loose fittings.
  • The water supply should also be checked for contamination. The local health department usually provides this service. Contaminated water is a major cause of illness in flooded areas.
  • Check the incoming electrical service for damage before turning on the power. Replace wiring, switches and outlets that were submerged or got wet during the flood. This will likely require the service of a licensed electrician.

5. Preventing future flooding

  • Patch cracks in the foundation and seal all basement walls. A polyurethane masonry caulk or filler is needed for this. For ¼-inch or larger cracks, apply hydraulic cement, which will expand as it dries.
  • Inspect crawl spaces and outside entry points to the basement. Patch all cracks in walls and the hardscape. Check all rain gutters for damage or leaks. Rain gutters should carry water away from the home and foundation.
  • Install a sump pump system with exterior perimeter drains if basement water continues to be a problem. Drains are 4-inch PVC drainpipe laid in gravel outside the foundation to carry water away before it enters the structure.

If the problem is high groundwater, this is a job for a professional. If at any point during your cleanup process you feel unable to complete the job, see problems you don’t know how to fix, electrical issues or are generally overwhelmed, it’s best to call in the pros.

Last Updated: December 28, 2012
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About Bill Washburn William "Bill" Washburn has a BA in advertising from the Art Center College of Design and has taught at the University of Southern California and Northrup University. Writing from a well-connected studio in the rural foothills of the west coast, he is a frequent speaker at local art associations and has published numerous articles discussing periods of art history and the fundamentals of drawing and painting. William is a master gardener who grows his own culinary herbs, organic heirloom vegetables and a variety of fruits. He writes frequently about his gardening experiences on his website Pioneer Dad. He is an accomplished advertising writer, fine art painter, and art director with more than 20 years' experience. 

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