Partner Blog

Information of use to those who serve private well owners.

FAQ: "Do Septic Additives Work?"


Should I use any additives in my septic system?


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.

New NHDES Online Tool Helps Well Owners Understand Their Water Sample Results

The New Hampshire Department of Environmental Services (NHDES) has developed a new free tool, the Be Well Informed Guide, for interpreting private well water testing results. Although the tool was developed for residents of New Hampshire, it's available to anyone. The tool provides an evaluation of water samples, identifying results that are over the USEPA maximum contaminal level (MCL), and can also recommend possible treatment options based on the sample results provided. The Be Well Informed Guide evaluates the pollutants that are part of the “Standard Analysis,” which is the group of commonly found pollutants is listed in the NHDES Private Well Brochure.

How the Tool Works

With water testing results in hand, all you need to do is go to the site and enter results from a laboratory report. You will then receive an evaluation of well water quality and, if necessary, possible water treatment options.

We entered an arsenic result of 15ppb (the USEPA MCL is 10ppb) in the example below. The tool allows you to use common units, so it’s much less likely a well owner will put in the incorrect units from their lab report.

We didn’t put in any other results, just arsenic, and when we hit “Submit”, got the following screen:

This illustrates that the tool is quite robust. Often the appropriate treatment options for a single contaminant, like arsenic, can depend on the overall chemistry of the water. Here the tool asks for more information to give you the best suggestion. We hit “continue”, and went on to the results shown below.

Based on your results, the tool will tell you if the value you entered meets, exceeds, or is close to the (federal) drinking water limit for public water supplies. Along with a detailed interpretation of your results, the tool will also identify health concerns and offer potential treatment options.

Access the Be Well Informed Guide.

Be sure to read all of the information related to use of the site. Also, please remember that The Private Well Class recommends using tools like this for an initial understanding of your test results. You should always take your results to a qualified health professional, such as your county or state health department, for the best advice.

FAQ: "Shock Chlorination Didn't Work"


I have shock chlorinated my well several times, but my sample results still come back positive for bacteria. What can I do?


Reoccurring bacteria problems mean there is a source of bacteria somehow connected to your well at the surface. It could be that your well is in a vulnerable geologic setting, meaning the groundwater itself is being contaminated from the surface and getting into your well. The other likelihood is that your well has a breach or was poorly constructed and allows near surface water into your well.  If your well is shallow, then the water coming into your well is from near the surface and more likely to be contaminated if there is a source nearby (usually livestock or septic). If so, this will always be an issue for your well. As an example, in New York there are many areas where a commonly used bedrock aquifer is at or near the surface, and because of this many shallow wells in this aquifer setting are vulnerable to surface contamination. Another vulnerable geologic setting is in karst areas, where you find caves, caverns, and sinkholes, all of which are conduits for surface contamination.

If you have a dug or bored well, they are made to allow water to seep into the well bore from the surrounding area over most of the depth of the well. They are typically more susceptible to surface contamination because of where water is getting into the well. If you have a deeper well, with casing to a considerable depth, it could also be that the well wasn’t properly constructed, maybe it wasn’t grouted properly so water can run down along the outside of the casing, or there are holes in the casing allowing water into the well from near the surface.

There are really only two solutions to this issue, properly construct a well into an aquifer that is not influenced by the surface (so in the NY example, it would have to be a different, deeper aquifer if one exists), or add continuous treatment to treat for the bacteria. The most common treatment is either a continuous chlorination or ultraviolet disinfection. If you are considering either of these alternatives, contact your health department for advice. Both have maintenance needs and you should understand the responsibilities of adding treatment.

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.