URBANA, Ill. – Heavy rainfall and flash flooding can lead to water accumulation in basements. According to a University of Illinois Extension educator, water in a small portion of a basement requires the same thorough cleaning and disinfecting as several inches across the entire basement.
“Receding floodwaters and infiltrated water may contain sewage and other contaminants, including pathogens that are harmful to people,” said Stanley Solomon, U of I Extension educator, energy and environmental stewardship.
“Mold is the long-term concern from the flood damage,” he said. “Mold can start growing on wet materials in 24 to 48 hours so it’s important to get all materials dried as quickly as possible.”
Water and electricity is a dangerous combination, Solomon reminded. “Don’t enter areas where electrical equipment or outlets may be exposed to the standing water,” he said.
Solomon recommends wearing rubber gloves, eye protection, and clothes that can be immediately laundered (or a protective suit) as a minimum. A proper fitting N-95, N-100 or HEPA-rated respirator/mask is recommended, especially if there is any indication of mold or if there have been overland floodwaters in the home from swollen streams and rivers.
Various water-soaked materials require different treatment plans:
- Remove porous materials such as drywall, carpet, and carpet pad that are wet or have indications of mold growth.
- Highly absorbent porous materials such as carpet padding, drywall, insulation, and furniture stuffing should be discarded in most cases. These usually cannot be dried quickly enough to prevent mold growth and are difficult to adequately clean.
- Non-porous materials such as glass, hard plastic, metal, and countertops can be cleaned with standard cleaning methods. A biocide such as chlorine bleach is not necessary.
- Semi-porous materials, such as structural wood, should be exposed to air as quickly as possible. Remove mold from these surfaces by scrubbing, or more aggressive methods such as sanding.
- Semi-porous materials, such as flooring and counter underlayment, may need to be removed to ensure that the structural elements can be properly dried. For example, vinyl flooring could be cleaned, but may need to be removed to dry or replace the subflooring.
Clean most surfaces with a non-ammonia soap or detergent. After cleaning semi-porous materials, disinfect the area using a bleach and water solution or another disinfectant. For cleaning surfaces, a mixture of one-fourth cup of bleach with one gallon of water should be adequate. The surfaces should remain wet for about 15 minutes to allow for disinfection. A higher concentration of 1½ cups of bleach per gallon is recommended for wood and concrete surfaces that cannot be thoroughly cleaned.
Do not mix ammonia and bleach, Solomon warned, because the fumes are toxic. Rinse the area with clean water and dry rapidly. Use fans, dehumidifiers, or ventilation to move the moisture from the area.
Finally, evaluate the source of the water intrusion to determine how it might be prevented from happening again.
Visit www.homemoisture.org for a national database created by Kenneth Hellevang with North Dakota State University Extension, which was drawn upon as a resource. Additional flood recovery information is available at www.ag.ndsu.edu/flood.