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Choosing The Best RV Holding Tank Treatment

March 15, 2018

What is the best RV Holding Tank Treatment? What is the better difference between rv toilet chemicals. Learn more.

Key Points:

  • There are four basic types of RV holding tank treatment: chemical/formaldehyde, enzyme, mineral/salt, bacteria. There are some products that combine one or more of these items, but the basic categories remain the same.
  • Wastewater management includes preventing/solving clogs in your plumbing lines or holding tanks and preventing/solving odors.
  • The wastewater system in your RV works by collecting used water and or waste inside either the gray tank or the black tank until you're ready to dump.
  • You should treat your wastewater systems because it will prevent clogs and help control odors.
  • Chemical/formaldehyde treatments are only effective at encapsulating waste, masking odors, and using caustic chemicals to break up larger pieces of waste into smaller ones.
  • Enzyme-only treatments break down larger pieces of waste into smaller pieces and help to prevent the buildup of waste residue. These treatments don't really reduce odors at all.
  • Mineral/salt treatments only eliminate odors. They do nothing to break down waste.
  • Bacteria treatments use bacteria to digest and liquefy waste, control odors, and prevent the buildup of waste or waste residue.


Updated November, 2019

We get asked all the time to help people select the best RV holding tank treatment, and of course we’re going to say that we believe it’s RV Digest-It! Come on, what did you expect us to say?

But seriously, besides shamelessly self-promoting RV Digest-It, let’s go in-depth and talk about what types of treatments there are, how they work, and what you should know about them before potentially setting yourself up for failure by using a dangerous or detrimental additive. Because, in the interest of being totally honest, some of the products that are available at your local RV parts store are just downright ineffective and bad for your RV, your health, and the environment.

Understanding the Different Types of Treatments

There are many types of RV holding tank chemicals, but the overwhelming majority of the products available fall into one or more of the following four major categories: 

  1. Chemical/Formaldehyde
  2. Enzyme
  3. Mineral/Salt
  4. Bacteria

Some products may be a combination of multiple product types. For example, there are numerous products on the market that contain both enzymes and bacteria.

Understanding Toilet Treatment Terminology

There are several terms people use when discussing RV holding tank treatments, but the idea is essentially the same: Wastewater Management. Here are a few of the more common terms you might come across:

  1. Toilet treatment
  2. Holding tank treatment
  3. Toilet chemical
  4. Tank additive
  5. Digester
  6. Odor remover
  7. Toilet Enzymes
  8. Tank Enzymes

What Is Wastewater Management in an RV?

Almost every RV has some form of built-in water capability. This may be a tank for fresh drinking water, a black tank that is connected to a toilet for holding human waste until it’s dumped, or a gray tank that holds the water from a shower, tub, sink, dishwasher, or washing machine until it’s dumped.

RVs come in every shape and style imaginable, containing many configurations, including multiple bathrooms, multiple tanks, and sometimes very unique plumbing systems.

These plumbing configurations are sometimes quite complicated, but when you step back and look at them, there are two basic problems that always require solving:

  1. Preventing/solving clogs from waste in plumbing lines and holding tanks.
  2. Preventing/solving odors from human waste.

In its most basic form, solving these two problems constitutes Wastewater Management. See this article for how your holding tank shape can cause build-up. You should make sure that your RV is clog and odor free; that way, you can enjoy your RV instead of wasting your precious vacation time with costly and often gross repairs! 

To learn some more basic info about RVs, how they're categorized, and how they work, touch or click here!

How RV Wastewater Systems Work

Motorhomes, trailers, fifth-wheels, boats, and RVs of all types normally come equipped with both gray water systems and black water systems that are designed to safely dispose of sink, shower, and toilet water in a camper.

When water and waste go down your sink or shower drains, they are deposited into a gray water holding tank that can either store the water until you get to a dump station (if you are dry camping) or can flow immediately into the sewer (if you are on full hook-ups).

Similarly, when water and waste go down your toilet, they are deposited into a black water holding tank to be stored until you dump your tanks. Regardless of camping type (i.e., dry camping or camping on hook-ups, all black tanks should always hold the waste (by keeping the black tank valve closed) until it’s dumped. Unlike a gray tank, the contents of a black tank should never be allowed to free-flow into the sewer (i.e., the valve being left open). This will lead to pyramid plugs and clogs! (Learn more about pyramid plugs and other clogs by reading our Unclogging an RV Toilet article!)

Reasons You Should Treat Your Wastewater System 

There are two major reasons why you should treat your waste water system:

  1. To ensure that solid waste and grease doesn’t lead to clogs and backups inside your holding tanks.
  2. To eliminate the sewer odors that tend to accumulate in the tanks and can permeate the RV.

Therefore, before we go any further, it’s important that we stress the two goals of a successful wastewater treatment procedure:

  1. Breakdown and digest solid waste.
  2. Eliminate odors

This might sound obvious to you, but many people don’t realize that these two points are the main reasons we treat RV holding tanks. Instead, for example, many people believe that the only purpose of treating an RV holding tank is to remove odors. Consequently, they neglect to prevent waste buildup in their holding tanks, which can cause them a host of worries and expensive repairs!

On the other side of the coin, unfortunately, many RV users erroneously believe that motorhomes, by their very nature, will always stink because of the toilets. They believe that the only reason you would use a tank treatment is to liquefy waste and prevent clogs. 

But here’s the truth: There is a huge difference between eliminating odors and masking them. Eliminating an odor means that you are actually removing either the source of the smells or the smells themselves. Masking an odor means that you are simply using strong fragrances to cover the smells. Basically, you are just replacing one over-powering odor with another, and this is never a pleasant nor effective solution!

In the long run, it's important to both use the right treatment product and implement the proper holding tank maintenance procedures, all of which are covered in The Unique Method, our comprehensive guide for treating RV holding tanks!

The Different Types of RV Holding Tank Treatments and How They Work

1. Chemical/Formaldehyde Holding Tank Treatments

There are several chemical treatments available on the market today. These sorts of products are some of the original toilet treatments, and when you purchase an RV, many will come stocked with a version of these chemical treatments in the cabinet. 

If you talk to older RVers, they will often tell you that these types of toilet chemicals are the only way to go, but most RVers consider this type of treatment to be outdated and something that should be avoided. You'll see why in a minute.

Chemical treatments are only good at:

  1. Encapsulating waste
  2. Masking odors
  3. Using harsh chemicals to break solid waste up into smaller pieces

Most chemical treatments use formaldehyde to keep stinky holding tanks under control. Formaldehyde is meant to encapsulate solid waste, kill bacteria, and mask odors inside your holding tank. All of this sounds okay until you understand that this is actually working against you in several key ways.

For one thing, the bacteria inside your holding tank are usually a good thing, so you don't want to kill the bacteria! Bacteria work inside your stomach and holding tank to break down and liquefy waste (i.e., paper and poop in your black tank and grease, fats, and oils in your gray tank). Keeping solid waste from accumulating inside your tank is important, otherwise you’ll get clogs. Moreover, you should make sure that you have good bacteria (aerobic) and not bad bacteria (anaerobic) inside your tank; this is crucial! We’ll talk more about bacteria below.

In terms of eliminating odors, chemical treatments can be effective at reducing odors by masking the smell with strong fragrances or by encapsulating the waste in a way that inhibits smell. However, odor masking is often not a preferred solution. You're simply replacing one strong smell with another. Additionally, encapsulating waste has its own consequences. By encapsulating waste, you’re physically preserving bricks and chunks of solid waste, so it’s only a matter of time before you get your first backed-up line or clogged holding tank. (If you should run into a clog, we've got you covered with this article!)

As if this wasn’t enough, it’s also important to know that formaldehyde should be considered a dangerous ingredient. You may not be aware of this, but formaldehyde has been linked to numerous severe diseases and health problems, including ALS and cancer. To top all of this off, formaldehyde is detrimental to the environment. 

Waste encapsulation is a big problem for septic and sewer systems, since formaldehyde makes it very tough for wastewater to perk naturally into the ground and can pollute waterways in septic systems. It also makes treating wastewater very difficult for treatment facilities.

In the end, although chemical treatments may help reduce toilet odors, the risks of using these products can be extreme.

It is ultimately your decision whether or not you should use a chemical/formaldehyde treatment. However, our recommendation is that you stay away from these types of RV holding tank treatments at all costs! 

An Example of a Chemical Holding Tank Treatment

2. Enzyme Holding Tank Treatments

Enzyme holding tank treatments are very common; they use enzymes to break down waste. As such, enzymes are often confused with bacteria, but they are not the same thing. Whereas bacteria are living organisms that can fully digest waste and convert it into water and carbon dioxide, enzymes are non-living proteins whose primary function is to break large pieces of waste or tissue into smaller pieces. Of course, this can help inside an RV holding tank because reducing the size and volume of the physical waste inside the tank will also help prevent clogs in the tank or plumbing lines.

Here’s what enzyme treatments do best:

  1. Breakdown waste
  2. Prevent the buildup of waste or residue 

Enzyme-based RV toilet chemicals are a popular solution, because they act fast in almost all temperatures and climates and are very effective at waste breakdown. The drawbacks to enzyme products is that, although they are great for breaking down waste, they don't completely eliminate it. They just make it smaller and more broken up. 

On the other hand, this is where bacteria shine. They fully eat and digest waste, leaving very little or no residual waste behind. Another benefit to bacteria which is not shared by enzymes is their ability to grow in size and strength. Because bacteria are living and able to reproduce, they continue to replicate while a food source is available. They’ll continue to reproduce until they've devoured and consumed all the waste, at which point they’ll die off and dissipate. However, enzymes do not grow in number like their bacteria counterparts. Simply put, if you start with 2 million enzymes, you will always have 2 million enzymes.

Probably the most significant drawback to enzyme treatments is that they don't have any odor controlling capabilities. They are simply unable to do anything for odors. After all, their only purpose is to breakdown solid waste! This is why many enzyme treatments use strong, odor-masking perfumes to control smells.

An Example of an Enzyme Holding Tank Treatment

3. Mineral/Salt Holding Tank Treatments

Mineral/salt holding tank treatments are a newer version of odor control products. These products often utilize mineral compounds to treat odors through a myriad of chemical processes. Here is what mineral/salt treatments do best:

  1. Eliminating odors

One common component in mineral treatments is zinc. Zinc comes in many forms, and some are quite effective at attacking odor-creating organisms inside your holding tank. Unfortunately, some of the forms of zinc used in holding tank treatments can be dangerous to humans and the environment, and they should be used with care. Several of these types of treatments are available today and are poorly labelled, misleading the consumer to believe they are safe or organic. This is simply not true. They are neither safe nor produced using organic farming techniques. As such, you should use them with caution, making sure to follow safe handling procedures. 

It should be noted that although these mineral/salt treatments are moderately dangerous for humans and the environment, they can be a very effective odor-elimination solution when used properly. When selecting a mineral/salt treatment, make sure you select a product that includes safe handling and dumping instructions and be cautious in trusting unfounded "safe" or "organic" claims.

An Example of a Mineral/Salt Holding Tank Treatment
  • Happy Camper Holding Tank Treatment

  • 4. Bacteria Holding Tank Treatments

    Bacteria treatments (such as RV Digest-It) are another very common type of holding tank treatment, and there are multiple things bacteria do very well:

    1. Breaking down waste
    2. Controlling odors
    3. Preventing waste/residue build-up

    Bacteria are living organisms, and when added to your holding tank, they multiply exponentially over time. Each individual bacterium creates their own enzymes to break down the solid waste into bite-sized chunks so the bacteria can consume it.

    There are two types of bacteria

    1. Anaerobic
    2. Aerobic.

    Anaerobic bacteria, most commonly found in your stomach, do not require oxygen to live. Unfortunately, during the waste breakdown process, they also create noxious gases as a byproduct (i.e., hydrogen sulfide gas, methane, etc.). This is why it smells when you pass gas. It is also why your holding tank smells so bad!

    Aerobic bacteria, however, require oxygen to survive and are the main component of high-quality bacteria-based holding treatments. Aerobic bacteria do not create noxious byproducts; instead, they create carbon dioxide and water as byproducts. So, as they break down solid waste, aerobic bacteria also replace the bad smells with fresh air.

    Good bacteria holding tank treatments introduce large amounts of aerobic bacteria to the holding tank, where they break down the waste and naturally remove odors.

    Bacteria, however, can be limited by high heat. When temperatures get above 85°F, bacteria become less effective. Nonetheless, most of these limitations are easily overcome if you understand how to properly treat your tanks. You can learn more about these proper tank habits here.

    Examples of Bacteria Treatments: 


    These are the four main types of holding tank treatments. Each one has its strengths and weaknesses. Hopefully now you are a little clearer on how they work.

    If you're looking for a comprehensive way to treat your tanks that covers not only the treatment but also all the procedures you'll need to put in place, we encourage you to check out The Unique Method, our guide for treating RV holding tanks.

    Below we have outlined our opinions on these four different types of treatments. (Surprise! We are biased!) Hopefully you will see that we make a compelling argument for and against certain treatment types. Feel free to jump ship here.... or keep on reading for a more nuanced and in-depth take on holding tank treatments as a whole!

    Sign up and get regular discounts on your favorite RV necessities. Unique Camping + Marine Holding Tank Treatments

    Our Opinionated Take on Holding Tank Treatments

    Chemical/Formaldehyde Products

    Many years ago, chemical products were the only treatments you would find in your local RV parts store. These products were introduced primarily to “encapsulate” or mask odors using chemicals or formaldehyde. These products don’t normally do anything to breakdown waste and unfortunately are normally quite dangerous. Formaldehyde, for instance, is dangerous for your health, and studies have shown it can actually cause cancer!

    The other frustrating byproduct of chemical or formaldehyde RV treatments is that they typically include incredibly foul-smelling fragrances in their formulas to help mask the smell of poop in your tank. If you’ve never smelled these products, it’s hard to explain how strong the fragrances actually are! However, many people claim that they smell worse than the actual toilet waste! 

    Also, because these products typically do nothing to break down waste, you’re essentially asking for backups and clogs that can send poop and pee back into your motorhome. And to top it all off, you’ll get to smell the over-powering smells of “cancer fragrance”! Needless to say, we strongly recommend that you avoid these types of products at all costs.

    Oh, and here’s the best part! Most of the major RV manufacturers install toilets by major toilet manufacturers who make these types of horrible chemical/formaldehyde products. Then they tell you in their instruction manuals that you need to use these nasty products to ensure your toilets work correctly! They probably even gave you a free sample when you bought your RV! Throw it away and start using a better-working, healthier, safer alternative!

    Enzyme Products

    Enzyme treatments are a great solution for quickly breaking down waste. Unfortunately, however, they do nothing to eliminate odors—unless they’re packed with odor-masking fragrances. 

    Many people confuse enzymes and bacteria, so it’s important to understand the differences. Enzymes are non-living proteins that literally break down waste. They take big chunks of your toilet waste, like toilet paper and feces, and break them down into smaller particles. They typically do this quite quickly.

    Besides doing next to nothing to eliminate odors, enzymes have other limitations. For one, unlike bacteria, they don’t grow in number. Simply put, if you pour 1 million enzymes into your black tank, you will still have 1 million enzymes in 20 years. On the other hand, if you use bacteria in your tank, their population will continuously grow as they “colonize” inside your tank.

    Another problem with enzymes is that they can potentially be dangerous to people who are allergic to enzymes. Therefore, it’s important that you don’t inhale any products that vaporize (puff into the air) and contain enzymes. This can often be the case for powder treatments that contain extra-cellular enzymes.

    Finally, although enzymes work very quickly and can perform well in extreme temperatures (either very high or low), they don’t necessarily eliminate waste. They simply make waste smaller. Only bacteria have the ability to completely eliminate (biodegrade) waste until it is completely gone.

    Mineral/Salt Products

    One of the more popular methods of odor reduction is to use minerals and salts to chemically neutralize odors. On the one hand, these products are great, because they don’t mask smells with heavy fragrances; however, they also do nothing to break down the waste—so get prepared for tank clogs and backups!

    Another very important thing to note about these mineral/salt products is that they are often dangerous—even though you would never know it by looking at their labels. Many of the top products contain Zinc Sulfate Monohydrate (or variations of zinc), and these are often labeled as “organic,” simply because they mine the salt or mineral from the earth.

    We hate to be the bad guys and point this out, but lots of dangerous things are mined from or found naturally occurring on the earth (like arsenic, asbestos, or formaldehyde)! Just because something is found in nature doesn’t make it “organic” or for that matter, safe! To be labeled as “organic,” a product must go through strenuous testing and validation and to our knowledge, none of the wastewater treatments that claim they are “organic” have ever gone through this testing.

    Frankly, we find it very frustrating that products labeled as “organic” are introducing dangerous ingredients into the confined spaces of your RV. Many of you touch these products with your hands or inadvertently inhale them on a regular basis, never realizing how dangerous they are to you, the environment, and marine life. These manufacturers have effectively green washed their products by claiming to be “organic.” Beware of these products!

    Full Disclosure

    Unique Tank Odor Eliminator contains Zinc (as well as waste-digesting bacteria), and when using it, safety precautions should be observed.

    You may ask (and rightfully so!), “Why would Unique make a product that isn’t safe when you’ve been known as the brand for safe products for over two decades?” It’s a good question and one that prevented us from making Tank Odor Eliminator for many years.

    To be entirely honest, customers kept asking for a product that would eliminate odor and break down waste in high temperatures and in low-water applications (like dry camping), and bacteria/enzyme cleaners like Unique RV Digest-It have very real limitations in those situations.

    We also knew that there were other products on the market using similar odor-reducing ingredients that routinely marketed themselves as safe and “organic” when they really weren’t.

    So, we set out to make a version that was self-contained in a drop-in pod so that users wouldn’t be forced to inhale the product or touch it like users routinely do with other competitor products that use scoops for their dangerous powder.

    Here’s the honest truth: If you have strong beliefs in using only safe products with the highest concern for the environment, then RV Digest-It is exactly the product you’re looking for. 

    If, however, you are routinely in situations (like high heat or dry camping) where odors are making your RV experience unbearable and unenjoyable, then you may consider using Tank Odor Eliminator, but you should be willing to overlook some of your green/health concerns. The choice is yours. 

    We’ll never make erroneous claims about this product being “organic.” We want you to be informed about the products you’re choosing to use, and we intend to be completely transparent and honest in these matters.

    Bacteria Products

    We saved the best for last: bacteria!

    Now before you say to yourself, “Ew! Did he just say bacteria?! I’ve spent my whole life pouring hand sanitizer on everything to make sure there are no bacteria in my life!” please hear us out! You’ll be glad you did!

    The truth is that bacteria have really gotten a bad rap for about the last hundred years; however, bacteria are incredible little natural cleaners! (How do you think food and trash biodegrades?)

    Every day, scientists discover new ways that bacteria greatly benefit our lives. Remember that people take probiotics, eat yogurt, and drink bacteria (Kombucha) to make sure their stomachs remain full of healthy bacteria.

    Truth be told, bacteria are one of the most under-appreciated organisms on earth. 

    All the same, we grant that there are some forms of bacteria that are dangerous. Luckily, however, the bacteria that are generally found in tank treatments are “non-pathogenic” bacteria. We only use safe bacteria in RV Digest-It, so that means it’s totally safe and healthy, just like the probiotics you take every morning!

    Why are bacteria so great for holding tanks?

    Bacteria are a natural waste digester and odor eliminator. Bacteria are living organisms (just like us!), and they require two things to thrive: food and water. Both of these are found in your holding tanks. Here's how it works:

    When you add a bacterial product to your holding tank, the bacteria begin to feast on the waste in your tank and eventually liquefy the contents of your holding tank—including, paper, feces, grease, and other solids. This ensures that you never get tank clogs or backups. One problem down!

    High quality bacteria products also replace the naturally occurring anaerobic bacteria with aerobic bacteria. As anaerobic bacteria from your stomach break down waste, they let off hydrogen sulfide gas (that nasty methane smell you get from your holding tanks and when you pass gas). Anaerobic bacteria are forced out by aerobic bacteria that let off carbon dioxide and water as they break down waste. This means complete odor elimination and no masking of odors! And it’s done by completely safe, natural occurring bacteria! It’s a beautiful thing, isn’t it?

    Key Takeaway:

    Bacterial products are the only treatment option that both digest waste and eliminate odors. Plus, they are the only option that are completely safe and natural! What more can you ask for?

    An important note: bacteria create enzymes; consequently, if you are using a bacterial product, you are also getting an enzyme product! The only goal of bacteria is to eat waste, but unfortunately they have very small mouths. Because of this, they need to break down the waste into smaller, bite-sized pieces before they can eat and digest the waste. To do this, bacteria create their own enzymes that take the big pieces and break them down into smaller pieces.

    Another incredible characteristic of bacteria is that they multiply and grow as they “colonize” the inside of your holding tank. This means that as they digest the waste, bacteria keep growing in number, and don’t forget that each one of them is producing more and more enzymes at the same time. So, if you start with 1 million bacteria, it’s only a matter of time before you have billions of bacteria and billions of enzymes.

    Quality Matters!

    The quality of the bacteria in a product is incredibly important. In order to get the most out of bacteria, you need to have high quality bacteria in the right strains with the correct formulations. Many bacterial products available today consist of cheap, watered down formulas and inefficient bacteria strains. Don’t assume that a product will work simply because it contains bacteria! Fortunately for you, RV Digest-It contains billions of the highest quality, best-formulated strains of bacteria in each and every treatment!

    If you would like to know more about Unique’s bacteria and what makes them so effective, we have written a more informative piece on how bacteria work.


    You have many choices for holding tank treatments, and we hope that this article has helped you to better understand what you’re pouring down your toilets and drains.

    Toilet treatments can be incredibly helpful in making your RV experience more comfortable and enjoyable. However, this is only true if you use high quality products that actually work.

    Like we mentioned above, we recommend that you be very cautious about what tank treatments you use. Some products can be very dangerous! Even if you don’t care how dangerous or environmentally detrimental many of these products are, you should know that you are literally pouring money down your toilet or drains with most of the commonly found treatments!

    Camping is an incredibly fun and memorable pastime, and it’s entirely possible to enjoy it without resorting to over-priced, dangerous, and ineffective products. Choose your products wisely, and you’ll never regret it!

    If you have questions about tank treatments or need further clarification, we’re always here to help! You may reach out to us at support@uniquemm.com.

    Happy Camping!

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