The United States Environmental Protection Agency (EPA) states “…these additives are not necessary for a septic system to function properly when treating domestic wastewater.”
Septic systems are naturally self-sufficient. Regular inspection and pumping to remove the solid sludge layer are essential for keeping your septic system in good shape. No additive can replace crucial maintenance.
Many of these additives or treatments claim to improve the overall efficiency of your system by breaking down the solids in your tank or reducing the odors. Vendors market their products as necessities that will repair a failing system or extend the life of your system.
Additive products at a local store/Photo by ISWS Staff
What are the types of septic tank additives?
Biological additives:
Biological additives:
These additives use bacteria and extracellular enzymes mixed with surfactants or a nutrient mix. However, human waste already contains an abundance of bacteria that is resilient and diverse, so there is no reason to add more.
Odor control additives:
Odor control additives:
These additives use chemical compounds that contain formaldehyde, paraformaldehyde, quaternary ammonia, and zinc sulfate that neutralize or mask odors by killing bacteria. This is counterproductive since your system requires bacteria to function properly. If your septic system has a smell, you need to have a professional inspect your system for any problems.
Solid reducing additives:
Solid reducing additives:
These are known as “flocculants” and cause the solids to clump and settle. Research results have been inconclusive but indicate that extremely large, uneconomical doses may be required to make a significant difference in effluent clarity.
It is also worth mentioning that there are other products that can harm your onsite wastewater treatment systems.
Inorganic compounds usually contain strong acids or alkalis and can be found in commercial drain cleaners. They can adversely affect the natural process of a septic system and can damage pipes, septic tanks, and other components if used frequently.
Organic solvents are products that commonly contain chlorinated hydrocarbons. They pose a significant risk to groundwater and wastewater treatment process causing many states to ban their use in onsite wastewater treatment systems.
Are the claims of the additive companies based on research?
The available scientific data regarding the effectiveness of additives is debated, even though several studies have been done over the past 40 years. The high number of products on the market and a lack of standard testing methods are part of the problem.
Are septic tank additives worth the cost?
These products can be expensive. A homeowner would receive more benefit hiring a septic system professional to perform regular maintenance on their system instead of paying the cost for additives. Also, using an additive may lead a homeowner to put off performing regular maintenance which could lead to even costlier repairs.
If you are contemplating using an additive, think about the reason why you are considering one. Do your drains empty slowly? Is there an odor? Consulting with your local health department, a septic professional, or an RCAP technical assistance provider can help you determine if there is a problem with your system and remedy the situation.
Can I use additives if I feel they do help my system?
Ultimately, a homeowner makes the decision on whether they will use an additive or not. Be advised that the EPA cautions against using additives in the Frequent Questions on Maintaining Septic Systems section on their Why Maintain Your Septic System webpage.
Also, keep in mind that some states and localities have state-specific rules and regulations regarding septic system additives. Reach out to your local health authority for more information.
Additives are not necessary for your septic system. A properly sized and maintained system is designed to function on its own. The use of additives may mask a problem and prevent a homeowner from getting necessary repairs done.
Additional Resources
Lee, B., Jones, D., Turco, R. Home & Environment: Septic System Additives. 2005. Purdue Extension.
Septic Tank Additives. Small Flows Quarterly. Winter 2002. Volume 3, Number 1.
Want to learn more about your private well and how to care for it?
Sign up for the free 10-week email course from PrivateWellClass.org. The class is a project of RCAP and the University of Illinois, with funding from USEPA.
Not finding the answer you need?
Send us a message in the chat or call us at 1-866-945-0699.