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Cleaning Sewage Backup

Kenneth Hellevang, Extension Engineer

Sewage contains pathogens that are harmful to people, so using personal protective equipment (PPE) is critical. Recommended PPE includes a HEPA-rated respirator/mask, rubber gloves, eye protection and protective suit.

Water and organic matter should be physically removed using shovels and wet vacuums or other water removal methods. After each use, all tools and equipment must be cleaned and decontaminated.

All porous materials exposed to the sewage must be discarded. They cannot be adequately cleaned. This includes carpet and carpet padding. Draperies should be professionally cleaned. Notify the cleaner of the problem. Clothes may be laundered with chlorine bleach or professionally cleaned.

Water and organic matter that can be removed using shovels and wet vacuums or other removal methods, in addition to the porous materials that are removed and discarded are considered the heavy contaminants.

After removing these heavy contaminants, thoroughly clean remaining materials. Clean non-porous and semi-porous materials using detergents and normal cleaning procedures. Do not mix products. For example, ammonia and chlorine bleach when combined produce a very toxic gas. A two-bucket approach is most efficient. Use one bucket for the cleaning solution and the other for the rinse water. After using the cleaning solution, rinse your mop, sponge or cleaning cloth in the rinse bucket. Wring it dry. Re-wet your mop in the cleaning solution. Using two buckets keeps most of the dirty rinse water out of your cleaning solution. Replace the rinse water frequently.

After thorough cleaning, use a biocide, such as chlorine bleach,  to destroy any remaining bacteria. Biocides are rendered ineffective by organic material, so meticulous cleaning is needed prior to a biocide application for the biocide to be effective. Use only biocides approved for the specific material and application. Assure that the biocide is labeled with an EPA registration number as a disinfectant. Follow the label on the biocide for concentration, contact time and safety guidelines. One option is wiping or spraying surfaces with a solution of ¾ cup of chlorine bleach per gallon of water and applying enough solution to keep the surface damp for at least five minutes. Refer to the label on the bleach container.

If sewage-contaminated water has seeped under the floor covering, the floor covering needs to be removed, even if the covering is not absorbent material. The subfloor needs to cleaned, dried and sealed prior to installing a new floor covering.

The structure should be dried rapidly to limit the potential for mold growth. No reconstruction should occur until wood is at less than 15 percent moisture or moisture content specified by the floor covering manufacturer. Other materials need to have dried to a low enough moisture content to prevent mold growth.

Reference: IICRC S500 Standard and Reference Guide for Professional Water Damage Restoration; Institute of Inspection, Cleaning, and Restoration Certification, 2nd Edition 1999.

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