Eliminating Holding Tank Odors In Your RV

Aerobic Bacteria Anaerorbic bacteria good bad rv camper motorhome trailer holding tank eliminating odors and smells

If you've been RVing for any length of time, it's very likely that you've experienced an extremely frustrating and disgusting phenomenon called RV holding tank odors! Plenty of RVers out there have struggled with this issue, and because it's so prevalent, some people end up giving up, assuming that there is no workable solution to this annoying and discouraging problem. But we're here to tell you: don't give up! There are very easy solutions to this problem. In this article, we will outline the root causes of RV holding tank odors as well as give you some workable solutions.

What causes odors in my RV holding tanks?

Before we get to the solutions, you need to understand the underlying cause of holding tank odors. In the most basic of terms, tank odors are caused when "bad" bacteria (anaerobic bacteria) inside your black and gray tanks emit hydrogen sulfide gas (that all-too-familiar methane smell) as they break down your waste! If you don't control the anaerobic bacteria inside your tank you're bound to have foul smelling, embarrassing odors. Luckily, with a solid understanding of what's happening inside your tanks and proper treatment you can eliminate these odors easily and affordably.

How anaerobic bacteria get into your tank and how you can get rid of them.

Inside your stomach, there are tons of anaerobic bacteria, which is a good thing! These bacteria help break down the food you eat and are a crucial part of the digestion process. When you go to the bathroom these anaerobic bacteria end up inside your black water tank. Of course, they continue to do their job here as well—break down and eliminate solid waste. The only problem is that they still emit hydrogen sulfide gas, and because the seals of your holding tanks can sometimes let small amounts of gas seep out of your tanks, you will probably smell these odors. This is where your toilet smells are coming from.

So, the trick to eliminating tank odors is getting rid of anaerobic bacteria.

There are two ways to do this:

  1. Kill them with chemical or mineral treatments
  2. Force them out with aerobic bacteria

Option #1: Killing Beneficial Bacteria

Caustic chemical treatments and many of the quote-on-quote “natural” RV holding tank deodorizers out there (like mineral or formaldehyde treatments) try to achieve odor elimination by killing the naturally occurring anaerobic bacteria inside your tank. This has two HUGE problems.

  1. By killing the bacteria in your tank, you're practically begging for a clog or backup. Bacteria are exactly what you want in your tank to keep waste liquefied. The only caveat is that you want the right bacteria.
  2. Many of caustic chemical products aren’t very good at fully eliminating the smells, so they also come with very potent fragrances that can be very overwhelming. In fact, some of these fragrances can be worse than the sewage odor you were trying to eliminate in the first place!

So, in summary, if you treat your tanks with these caustic chemical products, you’re opening yourself up to a clog, you're exposing yourself and your loved ones to potentially harmful chemicals, and, to top it all off, you could flood your RV with a potent fragrance that can be just as putrid as your tank odors! In other words, killing the anaerobic bacteria is a bad idea.

Option #2: Forcing Beneficial Bacteria Out

By treating your tank with a high-quality holding tank treatment that supplements your tank with good aerobic bacteria, you force out those bad anaerobic bacteria and replace them with good aerobic bacteria. As we mentioned before, anaerobic bacteria thrive in oxygen-free environments and emit foul smelling hydrogen sulfide gas during the breakdown process. Aerobic bacteria, however, thrive in oxygen-rich environments (like the inside of your holding tanks), and they release only carbon dioxide and water as they break down waste, which leaves your tank contents liquefied and odor free.

Effectively eliminating odors the right way

With all the above-mentioned information under your belt, it should be easy to see that the all-around most effective way to eliminate odors while also maintaining good solid waste breakdown inside your tank (so you don’t get backups) is to replace the stinky anaerobic bacteria with aerobic bacteria. Treating your tanks with a high-quality, bacteria-based holding tank treatment that uses high concentrations of top-quality aerobic bacteria strains to force out the anaerobes is crucial.

Unfortunately, many of the bacteria products on shelves today don’t have high concentrations of high-quality bacteria strains. Instead, many of them have low counts and inconsistent strains. This is mostly because either the manufacturers are trying to save on cost (high-quality bacteria are expensive!), or they don’t really know what they’re doing. We hate to say it, but there are numerous products on the market that are just private labeled junk, and unfortunately the companies selling these product don’t even know that they’re providing a low-quality bacteria product.

RV Digest-It comes in three liquid sizes, 32 oz., 4 oz., and 128 oz.

Using Unique RV Digest-It to effectively eliminate odors and digest waste.

With all that said, we've taken it upon ourselves to provide a solution in the form of a product that only uses the highest-quality strains of aerobic bacteria, keeps prices low, and is completely safe for you, your family, and the environment! And surprise, we're a little biased to our product, because it actually works!

RV Digest-It infuses a blend of naturally-occurring aerobic bacteria into your tank to replace the anaerobic bacteria and quench foul odors. It does this by breaking down the solid waste inside your tank while giving off only water and carbon dioxide. Unique’s proprietary blend of safe, eco-friendly bacteria is much more concentrated than competitors’ brands and outperforms competitors’ products by breaking down waste faster, eliminating odors better, and leaving behind no residue in your tanks to clog lines, foul up sensors, or degrade seals.

Simply put, Unique spares no expense in creating the highest-quality bacteria blends with concentrations that far exceed competitors’ products. This means better waste break-down and stronger odor removal. To top it all off, it’s less expensive per use than leading tank treatments!

Why are toilet odors lingering inside my RV?

Odors inside a holding tank are bound to happen on occasion, but if you are implementing the proper care habits, you shouldn't experience those odors inside your RV. When you smell odors inside your RV, it’s a good indicator that something isn't right and you need to address some problems!

Much of the information below is addressed by The Unique Method, which is our comprehensive guide for RV wastewater treatment. We'll talk more about The Unique Method later on in this article!

What follows are some common reasons for why tank odors make their way into your RV, along with tips on how to eliminate them. If you're interested in reading more about these issues and others, please follow this link to our article on How to Fix RV Odors!

Not enough water in your toilet

Water is a natural barrier for sewage gases. In your home toilet, there's a trap in the pipe that always keeps water in the line, which prevents sewer gases from seeping into your home. Not only does sewer gas smell terrible, but it also can be damaging to your health if you allow it to seep into your RV.

To ensure no tank odors seep into your RV, always keep a few inches of water in the toilet bowl whenever you are parked. This will create a water barrier (just like in your home's toilet). Obviously, you'll want to flush the water in your toilet before traveling so the water in the bowl doesn't splash out!

Not enough water is getting into your tanks

If you don't use enough water inside your tanks, the waste could dry up, killing the naturally-occurring bacteria. Of course, dead bacteria can’t digest waste, which means that your waste won't get broken down. This, in turn, can lead to odors. The solution to this problem is to flush your toilet often and generously. We recommend holding down your flush pedal for 10 full seconds every time you flush your toilet.

Your vents might not be working correctly

Again, just like your home, your RV is equipped with a vent that allows the naturally-occurring sewer gases to escape out the top of your RV so the smells don't back up into your RV. If you've already been following the right care procedures, and you're still experiencing odors in your tank, there is a good chance that you need to look at your exhaust system!

Several things can cause your exhaust system to under-perform. Outdoor temperatures or wind can force downward pressure on sewer gas, causing it to back up into your RV. Installing a vent cover, fan, or damper can help eliminate this problem. There are even turbines that will use the wind above your RV while you are moving or stationary to lift the sewer gases out and exhaust them into the air.

Because there are so many options available, try to "sniff out" (pun clearly intended!) the root of your problem to determine your best solution.

You can read more about this issue in this article.

It’s hot out there!

It's important to understand that bacteria are living organisms, and just like us, they tend to work less efficiently if temperatures get too high. This becomes a problem as heat starts to increase inside your tank.

To ensure the bacteria in your tank are performing to the best of their ability, be sure to regulate the temperatures in your tank. The ideal temperature for properly-working holding tanks is roughly 45 degrees Fahrenheit to 85 degrees Fahrenheit. If you encounter extreme heat and believe your tanks might be exceeding 85 degrees, you may need to pour some cold water or ice into the tank.

(Note: If you're camping in extreme cold, you'll likely experience similar problems with bacteria activity. When bacteria get too cold, they will start to work less effectively. Also, freezing sewage is also a concern. We recommend that you explore your options for ensuring that your holding tank is well-insulated. You may need to use a heater as well, depending on your situation. Please read this article for more on cold-weather RVing!)

Dealing With Odors In High Heat

When dealing with high heat, there are some very simple procedures you can follow to put an end to odors!

If outside or tank temperatures exceed 85 degrees Fahrenheit, do the following to make sure tank odors remain at bay:

  • Dump More Often. We recommend dumping your tanks every 4-5 days when high heat is a factor.
  • Add More Water to Your Tanks. Adding more water provides the living microorganisms (the bacteria) with the much-needed hydration, allowing them to keep working hard. Simply add more water with each flush or pour a few gallons into your tank if odors occur.
  • Follow The Unique Method, our comprehensive guide for treating your RV holding tanks. The Unique Method includes much of the advice already outlined in this article, detailing everything you need to know about proper holding tank maintenance.
  • Treat With Tank Odor Eliminator. The Unique Method recommends that you use RV Digest-It to help eliminate odors by replacing anaerobic bacteria with aerobic bacteria, but some people (especially those who camp in very high heat areas) find that supplementing RV Digest-It with Unique Tank Odor Eliminator helps to take odor control to the next level. Tank Odor Eliminator is a mineral blend that works in the highest heat to control strong odors in your holding tank. Best of all, Tank Odor Eliminator is designed to work perfectly with RV Digest-It for maximum odor control!
Unique Tank Odor Eliminator will treat your stink RV holding tank with a salt/mineral/bacteria blend. Treats odors in high heat in both gray and black tanks.

Odors in Especially High Heat

Our primary response to people dealing with foul odors in especially high heat situations is to use Tank Odor Eliminator in conjunction with RV Digest-It. Like we mentioned above, The Unique Method recommends the use of RV Digest-It to help control odors. In 99% of cases, you shouldn't need to use anything else. With that said, some people who camp in high heat choose to use Tank Odor Eliminator as a supplement to RV Digest-It, taking odor control to the next level. RV Digest-It is a completely safe and eco-friendly bacteria-based product, and Tank Odor Eliminator is a salt/mineral blend that completely controls odors even in the hottest temperatures. Together, these products will eliminate odors 100% of the time, no matter how hot it is.

To learn more about controlling odors in general as well as in high heat, read our article about treating odors in high heat as well as our comprehensive article that details all the different causes and solutions for RV toilet odors!

Salt/Mineral treatments are not always the safest products. Please follow all safety instructions when using this product for the best results. Read our disclaimer about Tank Odor Eliminator here.

A bit about Unique Tank Odor Eliminator:
  • Convenient and Easy-To-Use Drop-In Pod
  • Works in Black and Gray Tanks
  • Eliminates Odors Without Masking or Strong Fragrances
  • Liquifies Solid Waste in Tanks
  • Quickly Eliminates Odors in Extreme Heat Climates
  • Great For Dry Campers and Low Water-Use Applications
  • Formaldehyde Free
  • Made in the USA
  • Won't Harden in Toilets or Pipes

Beware Of Ineffective or Dangerous Chemicals

It is very important that you consider the solid waste in your tanks. So often, people only think about the odors in their tanks and neglect to ensure that the waste is being digested properly. Many of the popular "treatments" only eliminate odors or may even just mask them! They not only fail to digest waste, but they actually make the problem worse by adding heavy minerals to your system. These minerals coat your toilet bowl and lines, damage your tank sensors, and degrade the rubber seals that keep sewer gas from seeping out of your tank.

To ensure proper breakdown of solid waste, make sure your black tank valve is closed unless you are dumping (rule #1 of The Unique Method!) and use RV Digest-It to digest difficult solids like grease, toilet paper, and human waste. Ensure enough water is the tank so waste never dries up or becomes thick. Do not allow any chemicals or anti-bacterial soaps in your tanks. And NEVER allow flushable wipes into your tanks! For more on what items you should and shouldn't allow into your tanks, touch or click here.


So, now that we’ve given you the reasons why odors occur in your RV and tips on how to avoid them, here’s a recap:

  • Keep water in your toilet.
  • Make sure enough water is getting into your tanks so the waste doesn't dry up, killing the bacteria and making it impossible to digest waste.
  • Make sure your vents are working properly.
  • Take steps to counteract hot weather or cold weather, regulating tank temperatures.
  • Don't kill the bacteria in your tank by allowing chemicals into your holding tanks!

As we've said, most of these points come directly from The Unique Method, so we encourage you to check out that guide here!

Happy Camping!