What Could RV Chemicals Be Adding to a Septic System?

What Could RV Chemicals Be Adding to a Septic System?

Interested in Systems/ATUs?

Get Systems/ATUs articles, news and videos right in your inbox! Sign up now.

Systems/ATUs + Get Alerts

In August 2020, the University of Minnesota’s Onsite Sewage Treatment Program (OSTP) conducted a brief follow-up study of four commonly purchased recreational vehicle holding tank treatment products to understand how these types of products can impact the wastewater characteristics of an RV dump station. This was done after high levels were found in dump stations at septic systems at two state parks, both owned and managed by the Department of Natural Resources.

It’s assumed that the elevated levels could be due to a decreased amount of graywater usage from laundry and showering, but another source that could be contributing to higher contaminant levels could be RV holding tank treatment chemicals. These chemicals are typically used by campers to control odors in an RV’s holding tank. To help understand these higher levels the OSTP decided to test the BOD, COD and other parameters of a few of the most common RV hold tank treatment products available at Amazon.com. The purpose of this brief study is to determine how RV chemicals maybe impact wastewater contaminant levels. 

Four RV holding tank treatment products were evaluated in this study. The four products were selected based on their high Amazon sales and active ingredients. One of the products lists formaldehyde as an active ingredient. The chart shows the same wastewater concentration results from the November 2019 for comparison.

The Happy Camper product had the lowest reported levels of all contaminants evaluated. The only concern would be the pH, which was the lowest recorded and could drive the effluent overall to be acidic which could negatively impact the bacteria needed for wastewater treatment. 

The Aqua-Chem liquid product had a very high value of BOD and COD which indicated it will add a considerable load to a wastewater treatment system if used by most RV users at a particular dump station. The sample dissolved in 5 gallons of water also was on the acidic side, which could negatively impact the microbial community needed in a septic system. 

Both Walex products were relatively low in all contaminants evaluated aside from the phosphorus of the Bio-Pak at 57.5 mg/L, indicating it will add a considerable phosphorus load to a wastewater treatment system if used by a majority of RV users at a particular dump station.  

Based on this evaluation the chemicals used to essentially preserve the waste and perform odor control until the tank is pumped could be contributing to the elevated effluent levels found in RV dump station waste.

One of the active ingredients included in some RV treatment products is formaldehyde. In a study done for the Washington State Department of Transportation, it was reported that formaldehyde can create a very toxic environment for the anaerobic and aerobic bacteria in septic systems, impeding the ability of these bacteria to effectively treat effluent. If campers are using products that contain formaldehyde it can be very negatively impactful to the septic system. The study ruled out other ingredients that might be found in some treatment products such as dyes, perfumes, enzymes and detergents, finding they did not have as strong of a negative effect on a septic system as formaldehyde. 

It would be wise for RV parks connected to septic systems to educate campers to not add formaldehyde-based products to their holding tanks. Knowing it will be very difficult to nearly impossible to control the chemicals used by RV users, septic system operators and designers should be evaluating the waste stream levels including pH for treatment challenges. Along with the concentration of the waste stream due to limited use of water for showering and laundry, septic systems for RV dump stations should be designed based on mass loading versus hydraulic loading and include advanced pretreatment, of a size based on this loading. If excessive organic material or solids reach the soil system, the biological clogging mat can become restrictive to the point of hydraulic failure.

Flow data and more wastewater sampling for sites with RV dump stations and for the RV chemicals should be obtained to fully understand the general contaminant mass loading at an RV campground. It also must be noted that this assessment only included one round of sampling and the numbers represented should not be used as the sole characterization of the wastewater/RV chemical characteristics.

The complete report can be found at: https://septic.umn.edu/research.

About the author
Sara Heger, Ph.D., is a researcher and educator in the Onsite Sewage Treatment Program in the Water Resources Center at the University of Minnesota, where she also earned her degrees in agricultural and biosystems engineering and water resource science. She presents at many local and national training events regarding the design, installation and management of septic systems and related research. Heger is the President-Elect of the National Onsite Wastewater Recycling Association and she serves on the NSF International Committee on Wastewater Treatment Systems. Ask Heger questions about septic system design, installation, maintenance and operation by sending an email to kim.peterson@colepublishing.com.


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.