My RV Toilet Smells When I Flush

June 11, 2020

My RV Toilet Smells When I Flush Image of RV Toilet Bowl With Gross Smells Coming From The Bowl

Key Points:

  • Your toilet smells because stinky anaerobic bacteria from your gut produce methane odors while they break down the waste.
  • Odors smell more prominent when the toilet is flushed because the odors are able to travel up the toilet pipe from the black tank.
  • There are many products out there that can help you deal with odors, but some are more effective at eliminating odors than others.
  • Odors will worsen and waste breakdown will stall in hot weather if you're not using enough water in your holding tanks to cover the solid waste.

It's never fun to walk into a bathroom right after someone else has dropped a number two, but the smell usually dissipates pretty quickly. What if that same scenario cropped up in your RV but stuck around for hours, days or even years? This scenario has been reality for many RVers desperate for a solution to stinky RV toilets. In this article, we will briefly discuss what causes toilet odors, some resources for fixing them, and some additional recommendations for controlling odors in high temperatures.


Why Your RV Toilet Smells When You Flush

The toilet is the gateway to the black tank in your RV. Every time you flush the toilet, there is a pathway for odors from the black tank to rise up through the toilet pipe. The reason for a stinky black tank is obviously the human waste that is put in there. Inside your stomach, anaerobic (bad) bacteria break down food as a part of digestion, expelling the materials the body doesn’t need in the form of solid waste. This bacteria continues breaking it down inside the black tank because they are expelled along with the waste every time you poop. This means the stinky bacteria is trapped in the black tank with all the waste, which is paradise for them because that’s what they feed on. The trick to getting rid of that smell is to add bacteria that doesn’t create smells. Aerobic (good) bacteria are like bouncers who push out the trouble-making bacteria, eliminating tank odors.

Note: For more information on how both types of bacteria work in your holding tanks, refer to our guide on Why Are Bacteria and Enzymes Good for Your RV Holding Tanks?

By mentioning aerobic (good) bacteria, we are shamelessly foreshadowing our recommendation for the best way to fix a stinky RV toilet. In the next section we'll review some products intended to fix odors that really aren't as effective as they claim to be and others that may exceed your expectations.


How to Fix a Toilet Odor Problem

There are several ways to fix an odor problem with your RV toilet, but not all of them are methods we would recommend. Some may seem like they are fixing the problem when they actually can make it worse.


Kill the anaerobic bacteria with caustic chemicals

Lots of tank treatments out there are nothing but strong chemicals that kill all the bacteria in the tank. Some people do this with bleach, Pinesol, or other homemade treatments, but this tactic could lead to more odors, not less. When you kill even the stinky bacteria, there is now nothing breaking down the waste that's in the tank. Solid waste will still give off the poop smell even after the bacteria is dead because the bacteria leave stinky gases trapped inside the solid waste, and as water and urine soften it, those gases are released. The fact that waste breakdown is halted by this technique means that clogs are a distinct possibility as well. We recommend not using strong chemicals because it's not effective at controlling odors or preventing clogs, it could damage seals and other parts of the wastewater system, and it can be hazardous if spilled or inhaled.

Traditional chemicals will kill bacteria resulting in no waste breakdown and no odor control, but a zinc and enzyme product (coming soon to Unique Camping + Marine) will curb odors and still promote waste breakdown even though it will kill the bacteria. So while we always recommend using a bacteria and enzyme blend to treat your tanks, a high-quality zinc and enzyme product is also a fine choice despite its negative effect on bacteria. We talk a lot about the treatment products that are the best at eliminating odors altogether in our guide on Eliminating RV Toilet Odors.


Cover the smells with strong fragrances

Any time you see the term “RV Tank Deodorizer” or “RV Toilet Deodorizer,” be careful. Most deodorizers don't eliminate smells, they just mask them with more powerful fragrances that may smell better in theory but are usually so strong that they become just as annoying as the stinky smells. In addition to this underwhelming solution, most deodorizers include caustic chemicals that will kill the bacteria. So, not only are you adding an equally powerful smell, but you are also encouraging clogs by stopping the waste breakdown.


Use bacteria and enzyme treatments to push out odor-producing bacteria

This is the best option and the one we recommend because these products eliminate odors, promote waste breakdown, and the risk if you are exposed to it is low; you can take care of potential odor issues and prevent clogs all with the same treatment and feel safe doing it. High-quality bacteria and enzyme treatments (like Unique RV Digest-It) add a blend of aerobic bacteria and enzymes that doesn't produce odors and break down waste. But make sure you choose a bacterial treatment that is high-quality and draws upon various bacteria strains to harness the most effective breakdown results. High-quality treatments include bacteria strains that are sourced with the greatest care and quality in mind, so the resulting product returns powerful results.

We know that toilet odors are one of the biggest problems RVers face, so we created a guide that walks you through all the reasons you may be dealing with odors and how to eliminate them. We encourage you to review our guide on Eliminating RV Toilet Odors to start kicking those stinky smells to the curb, and further recommend that you begin following The Unique Method if you haven't already as it is specifically designed to prevent clogs and odors before they can ever develop.


Why are Toilet Smells Worse in Hot Weather?

Hot weather primarily causes more pungent smells because heat causes liquid to evaporate much quicker, which means that if you have liquid covering all the solid waste but high temperatures cause it to evaporate, it effectively removes the odor barrier. Evaporation causes the odor molecules to travel into the air with the evaporated water, which is what causes the odors to smell worse in high heat. Think of the last time you used a Porta Potty. A portable bathroom that smells like death probably has poop stacking above the waterline, but one that has water covering the waste doesn’t smell so bad. The water acts as a barrier to the sewage odor, and the same thing applies to your holding tanks. Don’t let high heat remove that water barrier and increase odors.

Not only does more water mean more odor barrier, but more water cools down the tank and slows evaporation, allowing the good bacteria you're adding to work more effectively. Aerobic bacteria slow down significantly in high heat, while the bad bacteria thrive in the high heat environment as they do in your gut, so keep the tanks cool and the waste covered with lots of water, and clogs and odors shouldn't be an issue. For more information on camping in hot weather and the importance of water in your holding tanks, refer to our guides on Controlling RV Holding Tank Odors in High Heat and Why Using Lots of Water in your RV Toilet and Holding Tanks is Crucial.

Odors are never an invited guest on your RVing adventures, and we have written a very comprehensive and detailed guide on Eliminating RV Toilet Odors so are armed with all the information you need to nip toilet odors in the bud as soon as they start!






Adopt The Unique Method

You bought your RV so you could enjoy life and spend time with family and friends. The last thing you want to do is waste precious time and money on fixing wastewater holding tank problems. Keeping your tanks in peak operating condition doesn’t have to be hard, confusing, or expensive if you follow our proven process: The Unique Method.

The Unique Method is a comprehensive tank care plan that we developed after years of conversations with real customers facing real problems. The Unique Method provides you with simple, preventative steps to stop odors, clogs, and sensor problems before they start so you can spend less time worrying about your holding tanks and more time enjoying the freedom and adventure of RVing. Try it yourself and see why thousands of campers trust their RVs with The Unique Method every day.

If you need more help with anything covered in this guide or simply have a comment, we’re here to help you anytime!

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