Partner Blog

Information of use to those who serve private well owners.

FAQ: "Do Septic Additives Work?"

Question

Should I use any additives in my septic system?

Answer

The short answer is no. A septic system works best on its own as long as it is maintained and the wastewater going through it is from normal household use. There is a huge market for additives claiming to make it function better or prolonging the life of the system, but research and experts agree, that its best to leave it alone, the bacteria we add naturally work best and don't need any help.

We interviewed a number of well and septic experts, and looked for actual research to support or refute claims of the benefits of additives. We found nothing definitive about the benefits of additives, but a number of things about the potential harm additives can cause, especially some chemical additives.

Two good resources on the subject are from the Purdue Cooperative Extension and the National Environmental Services Center (NESC), both of which are discussed below.  We also talked with 2 private well experts who manage state programs that work directly with well owners. Both said they, and other experts they have discussed this with, agree that there is no evidence to support that additives provide any benefit. They added that there is evidence that some chemical additives can damage the natural bacteria populations in a septic tank or allow solids to get into a septic field. Lastly, we contacted the USEPA, and their response followed suit, “Proper care and maintenance every 3-5 years (pumping the tank to remove solids) is recommended. All additives do is give the homeowner a false sense of security that their system will be fine if they add it.”

When we first answered this question as part of a septic webinar we conducted in the summer of 2015, we received a bunch of emails from homeowners who swear by their additives and some claimed to only pump their tank every 10 or 20 years. One stated that they had never had to pump their septic tank. We were given websites that provided “evidence” of a particular products success, even videos showing how they work. The problem with all of these testimonials are that the conditions of the testing are not the natural conditions in a tank. There was evidence to support these products under actual conditions in a septic system. These folks are likely in for a surprise at some point when their septic system fails and they either have septic effluent pooling in their backyard, or worse, backing up into their home. Also consider that in some cases the money spent on additives over a 3-5 year period would have likely paid for pumping and inspecting their tank.

Additional Resources

Purdue Extension - This handout does a great job of giving an overview of what the functions of a septic system are and how additives might affect it. It describes the types of additives that are out there, and how their use might impact a septic tank. They recommend good “habits” for how to improve performance of a septic system, by reducing the chemicals used every day that might harm the bacteria in a septic system, and best practices for reducing the amount of flow going through a system.  Improving daily habits can go a long way at preserving the proper function of a septic system.

NESC’s Small Flows Clearinghouse and Magazine - The National Environmental Services Center at West Virginia University has a national technical assistance hotline. The article at the link above was developed from calls they received from homeowners asking about additives for their septic systems. They describe some of the findings from several research studies on additives, but the question we are interested in, “Do I need to use additives…” is the last section on the 2nd page. My favorite statement, “Contrary to popular belief, yeast, dead chickens, possums, or raw hamburger do not need to be added to the septic tank”, pretty much sums up the folklore and home remedies that have made their way into this conversation.

Note: Hideyuki Terashima at the Illinois State Water Survey did all of the legwork to find and put together the resources used here on this topic. We originally used this information as part of a webinar on septic system issues in May 2015. As part of that webinar, we had a licensed septic installer and inspector participate in answering well owner questions.


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The Private Well Class is a collaboration between the Rural Community Assistance Partnership and the University of Illinois, through the Illinois State Water Survey and the Illinois Water Resources Center, and funded by the U. S. Environmental Protection Agency.