Unfortunately, one of the things that seems to be common to all new and experienced RV owners alike is that we’ve all fallen victim to bad smells emanating from the holding tanks of at least one of our coaches. In addition to it seemingly being a rite of passage for some new RV owners, it can also be caused by insufficient tank maintenance, an inherent problem with the RV plumbing system, or a clog, leak, or blockage. In this two-part article, I will discuss some ways to identify and eliminate or reduce RV sewer odor.

The first thing I recommend to new owners of pre-loved (ie: used) coaches is to thoroughly flush the holding tanks. Fill the black tank to flood level (above the level of the toilet seal). Leave the tank flooded for several hours, then recheck the level to ensure there are no leaks. Next, open the dump valve and with the valve still open, use a tank flushing wand or external tank flush connection to thoroughly flush the tank. Allow the tank to fully drain and ensure the tank level gauge shows the tank as empty. If not, continue the flushing process until the level sensors accurately show empty. If you are unable to achieve this, take the coach to an RV shop for assistance. Sometimes incorrect dumping procedures result in solid waste collecting in the black tank, causing odor and possible tank level errors. Remember to never leave the black tank dump valve open at a campsite, always wait until the black tank is at least 2/3 full before dumping, and dump the black water first, followed by the gray water.

I recommend replacing standard tank vent caps with toppers that utilize Bernoulli effect to suck odor out of the tank. One such device is the 360 Siphon, from 360 products. Active vent caps are often the single best way to eliminate tank odors. These vent caps are frequently so effective that you don’t need to use chemical in the tank. I suggest you try without chemicals first, and if you continue to experience odor, add chemical. When using tank chemical, always use natural product without formaldehyde and other nasty ingredients.

These simple procedures usually eliminate all traces of odor, but if they persist, you may have a problem such as a leak or crack in the tank or plumbing. You may choose to perform some basic checks, but damage to the plumbing system or holding tank will generally require professional repair by an RV service center.

In next weeks article, I will present some possible causes of persistent odor, as well as some basic preliminary checks you can perform prior to taking your RV in for repair.

For an additional look into RV Holding Tank Maintenance, be sure to          watch this video from our friends at RV Repair Club.

About the Author: 

Steve Froese, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.