Septic Care: Antimicrobial Products and Onsite Systems

Your customers’ use of antibacterial soap could be harming their septic system.
Septic Care: Antimicrobial Products and Onsite Systems

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Antibacterial soaps and wipes are now used by 75 percent of American households, according to a recent report. Products designed to kill microorganisms have become increasingly common in today’s homes. But how do these products affect septic tanks and septic systems, where microorganisms are essential?

To achieve proper treatment, a septic system is very dependent on millions of naturally occurring bacteria throughout the system. Daily, beneficial bacteria are added to septic systems, bacteria typically found in wastewater, our bodies, and other waste materials we dispose of via our septic system.

The use of antibacterial or disinfectant products in the home can and does destroy good and bad bacteria in the treatment system. Normal-use amounts of these products will destroy some beneficial bacteria but the population will remain sufficient and recover quickly enough to not cause significant treatment problems.

Excessive use of these products in the home can cause significant and even total destruction of the bacteria population in a septic system. Often the use of a single product or single application will not cause major problems, but the cumulative effect of many products and many uses throughout the home may add up to an excessive total and cause problems. In addition, with many of the products a greater amount is used when they are in a liquid form. More research is needed to determine what is “excessive” and which products are more or less harmful to systems.

What products are we talking about?
There are over 1,000 products that are concerning in relation to having a good bacteria community, including: 'antibacterial' hand soaps; tub, tile and shower cleaners; drain cleaners; toilet bowl cleaners; laundry bleach products; and others. Also included are 'antibiotics' that may be prescribed for medical treatment. These are products that are found in nearly all homes. “Antimicrobial” is the general term for any product or ingredient that kills or inhibits bacteria, viruses or molds. Disinfectant and chlorine bleach are common antimicrobials. Antibacterials, on the other hand, are only effective against bacteria. Lots of cleaning products and liquids now claim to be “antibacterial.”

If homeowners show resistance when you tell them they should go easy with the antibacterial products, science is on your side. There's a growing consensus that antimicrobial household cleaners won't keep them any safer from infectious illnesses than regular types. In 2000, the American Medical Association issued the statement that antibacterial soaps were no more effective against germs than common soap. Although they initially kill more germs than soap, within an hour or so there is no difference in the numbers of germs that have repopulated the area. In fact, experts say, it's not the type of cleaner that matters in combating germs, but the frequency and thoroughness of cleaning; plain soap, hot water and elbow grease are generally enough to do the job. As with antibiotics, prudent use of these products is urged. Their designated purpose is to protect vulnerable patients.

About the Author
Sara Heger, Ph.D., is an engineer, researcher and instructor in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is education chair of the Minnesota Onsite Wastewater Association (MOWA) and the National Onsite Wastewater Recycling Association (NOWRA), and serves on the NSF International Committee on Wastewater Treatment Systems. Send her questions about septic system maintenance and operation by email to


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