K-State Research and Extension News
February 17, 2009
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Septic Tank Additives Not Needed To Keep Systems Working Properly

MANHATTAN, Kan. – When an essential system is hidden away underground, it’s natural to wonder about its upkeep. Could a problem be sneaking up with no warning?

Such is the case with septic tanks, an essential part of the onsite wastewater treatment system used by many rural property owners, said DeAnn Presley, K-State Research and Extension soil management specialist. It’s only natural to wonder what kind of regular maintenance might prevent an unexpected problem. One possibility being promoted is the regular use of additives for the septic tank. 

“Property owners see and read advertisements all the time for various products that can be added regularly to septic tanks to keep them functioning properly,” Presley said. Limited third-party research studies have been conducted on these products, but the research that has been done is not promising, shesaid.

“This research has found no benefit in septic tank function to using any type of septic system additives. In fact, some additives potentially could be detrimental to the function or components of the septic system or to groundwater quality,” she said.

One research study, for example, found that the use of a biological additive caused the solid sludge layer at the bottom of the septic tank to decompose too rapidly, Presley said. This led to rapid gas production.

“As a result, solids floated up in the tank and were transported into the soil absorption field, which clogged soil pores, and led to reduced soil absorption rates,” she said.

Another claim sometimes made for biological additives is that they are beneficial for the microbe population or diversity in a septic tank. Additives are not necessary for “restarting” microbe populations after the tank is pumped, or after the use of harsh chemical products in the home (such as drain cleaners, heavy duty cleaning products, or disinfectants), she said.

“In a matter of a few days, microbe populations will become naturally re-established after the use of these products,” the soil scientist said.

A properly functioning and well-maintained septic system does not need septic tank additives at any time, Presley added.

“In fact, caution should be taken in using these products to avoid damage to the components or interference with the system function. Rather than spending money on additives, a wiser decision would be to have the septic tank pumped by a professional every three to five years,” she said.

More information is available in the K-State publication: MF2877 - Onsite Wastewater Treatment System Additives , which can be found online at MF2877.pdf or at county and district K-State Research and Extension offices.


Tips for Healthy Septic Systems

MANHATTAN, Kan.  -- There many things homeowners can do, or avoid doing, to keep their septic systems in good working order, said DeAnn Presley, K-State Research and Extension soil management specialist.

        Avoid using garbage disposals in homes that use onsite wastewater systems.

         Avoid flushing anything other than toilet paper. Items that are labeled as flushable, such as baby wipes and cat litter, may cause solids to build up in the tank and thus require more frequent pumping of the tank.

         Do not flush medications into the system. Certain medications may hinder microbial decomposition, which would also lead to more frequent septic tank pumping.

         If it has been more than five years since your tank was last pumped, consider calling a local onsite wastewater professional for maintenance and to have your septic tank pumped.

Nearly every county in Kansas requires inspection of onsite wastewater treatment systems when property is transferred, she added. 


K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by: Steve Watson
K-State Research & Extension News

DeAnn Presley is at 785-532-1218 or deann@ksu.edu.