June 29, 2021
“How do I get rid of odors coming from my RV toilet? I never have this problem at home.” Plenty of RVers (even seasoned pros) have struggled with this question, and because the issue of RV toilet odors is so prevalent, it's easy to give up and assume that there is no workable solution. So know that this is a common problem and you’re not alone; whether you’re new or experienced, toilet odor problems can happen to anyone. There are many “solutions” offered by fellow campers, online forums, RV service technicians, and websites that claim they will eliminate RV toilet odors, but we know from talking to thousands of RVers that these solutions provide very little help in cutting odors in their RV toilets. We want to help you unpack the misconceptions out there about RV toilet odors and the most effective ways to combat them. The tips and care practices in this guide will show you how to eliminate RV toilet odors, so don’t let anyone (even yourself) tell you that you just have to live with a stinky RV.
Let's clear up a slight confusion: almost every time you've experienced RV toilet odors, it's coming from the wastewater holding tank(s), not the toilet itself. After all, that is what the holding tanks are for: holding liquid and solid waste until you dump it. We all know how much odor can be created when we use the bathroom, but in an RV it can be worse because it's not being flushed away into an underground septic or city wastewater system; it's being moved from the toilet bowl to a tank under the RV floor. Until you're able to dump it, odors can always be a potential problem. Ideally, solid waste will be nearly liquefied while sitting in the tank because when you dump the tank, waste flows out using gravity; if the waste is too solid, it cannot flow out. The only way waste becomes nearly liquefied is because of the presence of lots of water and a healthy presence of bacteria and enzymes. They are like the scavengers of the microscopic world and break solid waste into its smallest possible size. So bacteria and enzymes are a very good thing in your tanks because they reduce the size of waste so it flows out better during dumps and remains under the water when it’s being stored inside the holding tank.
Okay, but what's making the smell? Bacteria is the reason for the smell, so you might wonder why we encourage bacteria in your holding tanks. Not all types of bacteria cause the smell. In fact, the smell is caused by the anaerobic bacteria that resides in your stomach. Whenever you use the bathroom, some of that bacteria comes out with the waste and it continues releasing odors even while in your RV's holding tank. The solution to pesky odors is not to kill the smelly anaerobic bacteria, but to replace it with bacteria that does not cause odors: aerobic bacteria. Each of these bacteria types perform the same function in different ways.
Aerobic bacteria (odor-free bacteria) must have oxygen-rich, water-filled environments, emitting only carbon dioxide and water as they break down human waste and toilet paper.
Anaerobic bacteria (odor-causing bacteria) don’t need oxygen or water to survive or thrive and release smelly hydrogen sulfide gas (the poop smell) as they break down waste.
Both of these types of bacteria will break down solid waste, which is an important process to control odors, but aerobic bacteria is the one you want working en force. Aerobic bacteria make it into your tank(s) when you add it by way of bacteria-based tank products. Both types of bacteria will eat solid waste inside the tank(s), but only aerobic bacteria can consume waste without creating unwelcome odors. In fact, they overtake the anaerobic bacteria, which means they actually contribute to eliminating odors. Knowing how bacteria contribute to waste breakdown in your holding tanks, you should also know that the type of tank treatment products you use can either destroy or boost the efficiency of the bacteria’s waste breakdown process.
Note: For more detailed information on how bacteria work and add value to the care of your wastewater holding tanks, refer to the Why Are Bacteria and Enzymes Good in RV Holding Tanks guide.
Now that you know the most effective way to eliminate odors is a 50/50 approach using high-quality products and following The Unique Method, we can cover some of the other common reasons for odor problems to arise. The fact is, even if you are treating your tank with a good bacteria treatment, you might still experience toilet odor issues, sometimes not related to your care habits or treatment choices.
With this in mind, we’ve compiled a list of some common toilet odor issues RVers experience and our recommendations for solving them. These issues can be persistent and in some cases seem unsolvable, but most of the time, using the right products and following The Unique Method will do the trick; however, if you are dealing with an especially persistent problem, please reach out to our customer support team.
Scenario 1: The poop in the black holding tank(s) is not covered by water
Make sure the solid waste inside your black holding tank(s) is completely covered by water. If you’ve ever used a Porta Potty (and most of us have) then you know what we’re talking about. A Porta Potty 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. The best, most convenient way to always have enough water in your black holding tank(s) is to hold the flush mechanism down for at least 10 seconds every time you use the toilet.
Scenario 2: Your toilet bowl should always have water in it (unless driving)
Your holding tanks aren’t the only thing that needs a healthy supply of water; you need to keep a moderate amount of water in your toilet bowl itself and refill it after every use, which adds yet another layer of odor control. You can add water to your toilet bowl by either partially holding down your flush pedal until the bowl fills or by choosing the “fill” option on your toilet if your RV is equipped with this feature.
Scenario 3: The odor-free bacteria can’t survive and thrive
Use products containing good, aerobic bacteria (like Unique RV Digest-It) in conjunction with ample amounts of water to push out the stinky, anaerobic bacteria. Aerobic bacteria must have ample amounts of water to survive and reach the waste; if your flushing habits do not include allowing a lot of water into the tanks, the bacteria may not be working at their highest potential. The easiest way to ensure enough water in the holding tank is to hold down the flush pedal for 10 seconds every time you flush. By adding aerobic bacteria and ensuring generous amounts of water in the tank(s), the waste will still break down, but you won’t have to deal with the smell!
Scenario 4: High heat is causing water evaporation or adverse environments for aerobic bacteria
Because excessive temperatures can cause water to evaporate from your toilet bowl and/or your holding tank(s), it becomes doubly important to use plenty of water. Water can evaporate at any temperature above freezing, but the higher the temperature, the more water evaporates. After conducting brief tests, we found that when parked on concrete or asphalt, tank temperatures nearly match the outside ambient temperature but were about 10 degrees cooler when parked on grass or dirt. This means if you’re slowing down because of the heat outside, the bacteria in your tanks probably are too. In high temperatures, rapid evaporation will quickly lead to exposing solid waste above the water line and diminishing the vigor of the aerobic bacteria. So if you know you will be camping in a place where temperatures get consistently high (above 85 degrees), it’s good practice to add more water to your black holding tank(s) than you normally would. Honestly, you can never use too much water (until you need to dump the tanks, of course). The more water you use, the less odors you will experience!
Something that can severely limit the effectiveness of the aerobic bacteria and increase odors is hot weather. It's the perfect breeding ground for sewage odors. There are several reasons why hot weather makes smells worse in your RV:
First off, how do I know that my holding tanks are too hot? We knew this question would come up, so we conducted some brief testing of holding tank temperatures and found that when parked on concrete or asphalt, tank temperatures nearly match the outside ambient temperature but were 10 degrees cooler when parked on grass or dirt. This means simply attaching a thermometer on the outside of your RV will give you a pretty solid reference for what your tank temperatures might be; if it’s 95 degrees outside, that means it’s probably too hot in your holding tanks. It’s also important to note that while traveling on asphalt roads (especially at high speeds) the heat created from the vehicle or RV engine will pass under the RV and contribute to even higher tank temperatures, so be aware of this when moving your RV to a new location in high temperatures.
The easiest, most basic first step for addressing hot holding tanks is to use more water! It might seem redundant at this point, but using more water in your holding tanks will help cool the tank (you can even put ice in there to cool it faster). Aerobic bacteria perform much better in cooler temperatures, ideally within a range of 45 degrees to 85 degrees F; after all, they are living organisms that require food (solid waste), water, and moderate temperatures to thrive. Using a generous amount of bacteria and enzyme treatment products, like Unique RV Digest-It, is also very important when RVing in hot weather. Most of the time, increasing the amount of water and bacteria-based tank treatment will keep odors at bay, but in extreme heat circumstances, it may be necessary to supplement your bacterial tank treatment with an odor eliminator, like Unique Tank Odor Eliminator.
Unique Tank Odor Eliminator is a zinc-based product that is very effective at stomping out odors. However, all zinc-based products must be handled more carefully than bacteria and enzyme products, and many companies do not package zinc products as responsibly as they should, so be cautious when using them. Fortunately, we combine peace of mind and convenience by delivering Tank Odor Eliminator as drop-in pods instead of loose powder which can easily be inhaled or spilled onto the skin. We recommend this product or a new Unique zinc and enzyme blend (coming soon) for dry campers and boondockers who typically use less-than-ideal amounts of water or camp in hot weather; both of these zinc products are also very effective in galley or gray tanks. If you choose the zinc and enzyme blend over a bacteria-based treatment, the solution is still the same: dump more often (if possible), use more water in your wastewater tanks, and use your zinc and enzyme treatment generously.
Tip: Read more about controlling odors in high heat situations in our Controlling RV Holding Tank Odors In High Heat guide.
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. Freezing sewage can also pose a problem since liquid expands when it freezes; a very full tank could crack or become warped during the freezing process. We recommend that you explore tank insulation options like wrapping your tank with insulated materials or using a tank heater. For more details on cold-weather RVing, refer to the How to Keep Your RV Holding Tanks From Freezing guide.
Scenario 1: You’re using counter-productive tank treatments
Always use a high-quality product that will effectively break down waste and control RV toilet odors. The best products to accomplish this are bacteria and enzyme blends (like Unique RV Digest-It) or zinc and enzyme blends (coming soon). A bacteria and enzyme blend will replace smelly anaerobic bacteria with odorless aerobic bacteria; a zinc and enzyme blend will kill any bacteria in the tank, but the rapid and effective breakdown ability of the enzymes and the strong odor control of the zinc provide a similar level of odor elimination and waste breakdown. Enzyme-only treatments can help with waste breakdown, but enzymes alone cannot eliminate odors because all they do is break apart waste into smaller pieces; this solution may work for a short weekend camping trip, but extended trips may require different treatments.
Many chemical treatments kill bacteria as a by-product of covering the odor with a more powerful, but equally unpleasant smell and will also stop or severely limit waste breakdown, which can lead to clogs, sensor misreadings, and plenty of odors. These chemical treatments often include minerals that could damage tank sensors, erode rubber seals, and can also negatively affect the environment and the human body. Some people employ varying homemade remedies, but our conversations with RVers have shown us that these homemade treatments often include chemicals, promise a lot but deliver very little, and should simply be avoided.
Scenario 2: You’re using cleaning products that are neutralizing your bacteria-based tank treatment
If you’re using high-quality bacteria and enzyme tank products like RV Digest-It, sending chemical toilet cleaners and antibacterial dish soap down the drains will kill the tank-dwelling bacteria and negate their breakdown power. Use a bacteria-enhancing toilet bowl cleaner (like Unique RV Toilet Cleaner) instead of a bacteria-killing cleaner and a non-antibacterial dish soap (like Dawn Ultra). It is also important to use non-antibacterial dish soap to clean your dishes and wash your hands if you are using bacteria and enzyme treatments in your gray/galley tanks. Refer to the WTF - What to Flush guide for more details.
Scenario 3: You’re smelling the strong perfumes from your toilet odor solution
Be warned; many deodorizing treatments out there are just stronger, “less pungent” smells than the stinky poop odors you’re trying to remove. They often operate like a Glade aerosol spray or Febreze freshener spray does in a bathroom; it just fills the air with a smell that’s not as rancid as the bad smell but still makes your head swim. By using toilet odor control treatments that only mask odors, you’re just putting a band-aid on the problem and potentially creating another if the deodorizing treatment contains bacteria-killing chemicals, which is the last thing you want to put into your bacteria-rich tank environment.
Scenario 1: Your RV is parked in a way that prevents sewer odors from properly venting
If you position your RV a certain way, the wind will be able to blow vented odors back inside rather than allowing them to disperse into the outside air. For instance, some RVs have vents on the side, so you will want to make sure that side is facing the direction the wind is blowing. For other RVs where the vent is located on the roof, cyclone sewer vents can be attached to the top of the vent pipe. These vent supplements act like weather vanes, following the wind and creating a vortex that pulls odors up and away from your RV.
Scenario 2: Vents weren’t installed correctly
It may seem unlikely, but have your ventilation system inspected to ensure it was properly installed. Sometimes the hole in the ceiling of your RV where the vent would go was mistakenly never cut, which means none of the toilet odors can escape. Proper inspection and repair of your ventilation system can help to fix this issue.
Scenario 3: Vents are clogged with debris
Whether your vent is on the top of the RV or the side, debris can still collect inside making it harder for odors to escape. If you are certain your vents were installed correctly and your RV is parked in a way that should allow odors to dissipate, you may need to check the inside of the vents. In high wind situations or simply over time, leaves, organic debris, and even living things can get stuck inside the vents. It’s good practice to check that all your vents are clear of debris as regularly as possible and certainly for seasonal campers at the start and end of the season.
Scenario 4: Leaks and broken seals can slowly release odors
Check your system regularly for damage to seals. Your tank ventilation system should be sealed completely from the inside living space of your RV, so if you are experiencing persistent odors despite adding water and more tank treatment, you may have some leaks or broken/fatigued seals. And this is no time to just add some deodorizing pods and move on, because if your ventilation system is compromised, it can cause damage to the tanks or eventually engulf the living space with overwhelming odors. So it’s important to inspect your seals regularly. The good news is that when you use Unique Camping + Marine products to treat your tanks, it helps soften the seals, extending their functional life.
Scenario 5: Sewer gas is backing up into your RV through your black tanks (for hook-up campers)
Keep your black tank valve closed even while on hook-up. If you’re following The Unique Method (and you should be), you’ll know that keeping your black tank valve closed is the cardinal rule of black tank care. Unless you’re dumping a full tank, your black tank valve should always stay closed. Otherwise, all the liquid will continually flow out of your tank, and you will be left with an exposed pile of stinking poop (which can develop into a pyramid plug) that cannot be digested by the aerobic bacteria (the odorless one that needs water covering the waste). An open black valve even on hook-up means that there is no barrier to stop gases from the sewer hook-up from wafting backward into the tank and eventually the living space. Not only are these offensively smelly, but high levels can be hazardous because they contain methane.
Scenario 6: Gray tank odors are backing up into your RV
For hook-up campers who keep their gray tank valve open, put a p-trap (pictured here) in the hook-up hose to prevent sewer gas from backing up into your RV and deep clean your gray/galley tank(s) regularly. While you might think odors wafting from the hook-up line through the gray/galley tank would smell like sewage, many RVers have reported it’s more like a pungent garlic smell, which isn't much better than a poop smell; a p-trap uses water to block those odors from ever entering your gray tank(s).
For dry campers (boondockers) who have to keep their gray tank valve closed, odors can back up into your RV from accumulation of grease and soap scum waste inside your gray or galley tank. This is due to the residue not only from food grease, but also from soap, shampoo, conditioner, and even human hair that gets into the tank. It’s also important to make sure no solid food waste goes down the drain; always wipe your dinner plates before washing them and/or use a drain strainer to catch large chunks of food that could otherwise end up in your gray tank(s). Aside from good camping habits, you also need to treat your gray/galley tank(s) regularly with bacteria and enzyme treatments like RV Digest-It and deep clean them regularly with Dawn Ultra dish soap.
Note: For full-time RVers, the deep cleaning process looks a little different because typically you still have to use your tanks while deep cleaning them. For more details about how to deep clean your gray and black holding tanks, refer to the Deep Cleaning RV Wastewater Holding Tanks guide.
Scenario 1: Residual waste buildup inside your wastewater tank
Waste buildup can happen for a variety of reasons, many of which we’ve already covered: leaving your black tank valve open, lack of water in the tank(s), and using chemical treatments instead of high-quality bacteria and enzyme products or zinc and enzyme products. Additionally, if you’re not flushing/rinsing your tanks regularly (at least every 3-5 dumps), waste can hide in corners and crevices. If your RV does not have a built-in rinser wand, you can use a reverse jet flush or tank cleaning wand. It might seem like leaving a little bit of waste in your black tank(s) isn’t a huge issue, but letting a tiny piece of food rot in your refrigerator for years will stink just as much as a larger piece of rotten food. The same applies to your holding tanks. Even a tiny amount of residual waste can cause odors you’d think would only come from larger pieces, so it is crucial to regularly flush it out. Refer to these guides for more details on the importance of flushing your tanks:
Scenario 2: Stationary units accumulate residual waste in holding tanks because they’re out-of-level
This is another reason you should perform regular, long rinses on your holding tank(s); waste can accumulate in the low points of an out-of-level holding tank. Many people who live in RVs for extended periods of time will have issues with residual waste buildup. Your holding tanks use gravity to drain, but no matter how level you think your holding tank is, there is almost always a low point where waste can slowly build up until there is a block of poop stuck inside your tank, which can cause odors and clogs. Regular (typically biannual) use of a good bacteria-based deep-cleaner (like Unique Tank Cleaner) along with regular, long rinses of your tank(s) should fix and prevent this sneaky problem. Rinse your tanks by using a built-in tank flush system, rinsing wand, or valve-mounted tank flusher, or just fill your tank with fresh water and dump the tank several times.
Proper RV wastewater tank maintenance is a 50/50 approach: 50 percent in the type of products you use and 50 percent in the care habits you practice. You need the best of both to achieve the aromatic bliss you desire in your RV. Adding a single bottle of treatment to the tank and walking away will just temporarily provide false peace of mind. If you're not pairing high-quality tank treatments with regular, healthy cleaning habits, problems will continue to emerge at the most inopportune times. Your goal is to control toilet odors and promote waste breakdown, but not every treatment product will deliver the all-encompassing results you are searching for.
Many of the top name brands or homemade treatment solutions tend to address only one problem like odors instead of controlling everything in one treatment (odors, waste breakdown, keeping sensors clear of debris, non-corrosive to tanks and seals, etc.). Waste breakdown and odor control are actually connected because nearly liquefied waste is always less smelly than piled up waste. But how exactly do you get waste to liquefy? The type of treatment product you use will either end waste breakdown or boost it, so be informed about the product you use in order to get the most effective waste breakdown happening in your tanks.
Top name brands often contain harsh chemicals that many RVers are trying to avoid nowadays, and many times their labels are misleading or silent when it comes to product ingredients. Harsh chemicals like formaldehyde or bronopol will kill all bacteria in the tank, so chemical-based tank treatments will actually halt the waste breakdown process, meaning an increased risk for RV toilet odors. Chemical treatments also have the potential to cause damage to tanks, valves, and seals. From conversations with hundreds of RVers, we also know that homemade treatments, which usually include chemicals, deliver little benefit and sometimes can even worsen the issue.
Enzyme only treatments can be beneficial in some circumstances and are certainly better than chemical treatments because enzymes don't damage tanks and seals and they break down waste very quickly; however, they have no odor control power. The best choices to take care of all the potential tank problems are either bacteria and enzyme or zinc and enzyme treatments. Bacteria and enzyme treatments are the gold standard, but zinc and enzyme treatments take the silver medal.
Bacteria and enzyme treatments will add a blend of aerobic bacteria and enzymes to your tank to help break down the waste and push out the stinky anaerobic bacteria that is constantly being added every time you use the toilet. This means that if the goal is to eliminate waste buildup and odors by adding odor-free bacteria to your tank, you need to carefully select the types of cleaners and dish soaps you’re using in the living area of your RV. Using chemical toilet and shower cleaners and antibacterial soap will counteract all the benefits of the bacteria-based tank treatment once they go down the drains. Bacteria and enzyme treatments are also the most mild and responsible blends when it comes to environmental and human exposure. Keep in mind, however, that it is especially important to be consistent with your healthy tank care habits when using bacteria and enzyme treatments; aerobic bacteria need a very specific environment (plenty of water and moderate temperatures) in order to flourish and work at their best.
Zinc and enzyme products will actually kill bacteria, but the enzymes break down the waste quickly and the zinc takes care of any odors. We always recommend bacteria and enzyme treatments first because zinc-based treatments are not quite as friendly when exposed to nature or humans, but in cases where frequent dumping is unlikely and water usage in tanks is limited, zinc and enzyme treatments will effectively take care of odors and waste breakdown. Even with this product, healthy care habits are important; enzymes and even the zinc use water as a pathway to break down waste or zap odors, so the more water in the tank, the more effective the treatment.
Note : For a more detailed explanation of the different treatment products available and their effectiveness, refer to The Unique Method guide.
A good treatment product is only as good as the treatment process you are following, and we have created a proven tank care process called The Unique Method that will help you maximize the effectiveness of the treatments you are using. While almost any treatment, even ones we don’t recommend, can work with The Unique Method to deliver some level of success, we constantly recommend using our products because they were specifically designed to work most efficiently with The Unique Method. Bacteria and enzyme products (like Unique RV Digest-It) will work most efficiently, but our zinc and enzyme product (coming soon) will also deliver outstanding results when paired with The Unique Method.
Knowing the pitfalls and benefits of available tank care products is crucial, but there are also things you can do to take your odor-control expertise to the next level.
Guide Continued Below
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RV toilet odors are easy to avoid when you use high-quality treatment products and employ the right care habits. We’ve gone through a lot of detail in this guide, but the basic idea boils down to this:
Follow The Unique Method consistently
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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