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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.

Updated June, 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 is 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, 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

Holding tank treatments come in four major variations

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 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. Even though there are many ways of saying it, the idea is essentially the same: wastewater management. Here are a few of the more common terms:
  • Toilet treatment
  • Holding tank treatment
  • Toilet chemical
  • Tank additive
  • Digester
  • Odor remover
  • Toilet Enzymes
  • Tank Enzymes
What Is Wastewater Management In An RV?

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

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

When you step back and look at these, sometimes complicated, plumbing configurations, two basic problems always require solving:

  1.  Preventing / Solving Clogs From Waste In Plumbing Lines and Holding Tanks
  2. Preventing / Solving Odors From Human Waste
This is what constitutes Wastewater Management. Making sure your RV is clog and odor free, so you can enjoy your RV instead of wasting your precious vacation time with costly and often gross repairs.
How RV Wastewater Systems Work

Motorhomes, Trailers, 5th Wheels, Boats, and RVs of all types normally come equipped with both Gray Water systems and Black Water systems that are designed to safely and healthfully dispose of our sink, shower, and toilet water in our campers.

Diagram of how a grey tank and black tank drain to a waste valve in a simplified way


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-up).

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. ALL black tanks, regardless of camping type (dry camping or camping on hook-ups) should always hold the waste (by keeping the black tank valve closed) until it is dumped. Black tanks should never be allowed to free-flow into the sewer, with the valve being left open. This will lead to pyramid plugs and clogs. More on this later.


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We treat our waste water systems for two major reasons:

  1. To ensure the solid waste and grease inside the tanks don’t turn into clogs and backup the holding tanks
  2. To eliminate the sewer odors that tend to accumulate in the tanks and can permeate the RV


    So, before we go any further, it’s important to remember that the two goals of a waste treatment is twofold :

    1. Breakdown and digest solid waste
    2. Eliminate odors

    This might sound obvious to you but many people don’t realize that these are the reasons why we treat RV holding tanks. Many think the only purpose of treating RV tanks is to remove odors and neglect to prevent waste buildup in their holding tanks.

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

    A good tank treatment should do both! It should effective liquefy waste and eliminate odors.

    The last thing to mention before we jump into discussing the different types of treatments is there is a HUGE difference between eliminating odors and masking them. Eliminating an odor means you are actually removing either the source of the smells or the smells themselves. Masking odors means you are simply using strong fragrances to cover the smells – basically replacing one over-powering odor with another. This is never a pleasant solution!

    Now that you understand some of the basics, let's jump in! 

    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. They are some of the original toilet treatments and many RVs come stocked with a version of them in the cabinet when you purchase the RV. 

    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 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 your stinky holding tank 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, bacteria inside the holding tank is usually a good thing, so you don't want to kill the bacteria. Bacteria are working inside your stomach and holding tank to breakdown and liquefy waste - 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 so you don't get clogs. Making sure you have the good bacteria (aerobic) and not the bad bacteria (anaerobic) inside your tank is also crucial. More on bacteria later.

    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. Odor masking is often not a preferred option as you're simply replacing one strong smell with another. Encapsulating waste has its own consequences. By encapsulating waste you are physically preserving bricks and chunks of solid waste, so it is only a matter of time before you get your first backed-up line or clogged holding tank.

    It is 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 as it makes it very tough for waste water to perk naturally into the ground and can pollute waterways in septic systems. It also make treating waste water very difficult for treatment facilities.

    So, though chemical treatments may help reduce toilet odors, the risk of using them can be extreme.

    Whether you choose to use a chemical / formaldehyde treatment is ultimately yours. Our position is to stay away from these types of RV holding tank treatments at all costs.

      Examples Of Chemical Treatments: 


      2. Enzyme Holding Tank Treatments

      This type of holding tank treatment is very common and there are many products that utilize enzymes to break down waste. 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 to water and carbon dioxide, enzymes are a non-living proteins whose primary function is to break large pieces of waste or tissue into smaller pieces. 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 are what enzyme treatments do best:

      1. Waste Breakdown
      2. Preventing Waste Build-Up / Residue 

      Enzyme 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 enzymes is that, though they are great for breaking down waste, they don't completely eliminate it. They just make it smaller and more broken up. This is where bacteria shine. They fully eat and digest the waste, leaving very little, or no, residual waste behind. Another benefit to bacteria, 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, until they've devoured and consumed the waste, at which point they die off and and dissipate. Enzymes, however, do not grow in number like their bacteria counterparts. Simply put, if you start with 2 million, you will always have 2 million enzymes.

      Probably the most major drawback to enzyme-only 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.

      Examples of Enzyme Treatments: 


      3. Mineral / Salt Holding Tank Treatments

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

      1. Odor Elimination

      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 forms of Zinc that are used in holding tank treatments can be dangerous to humans and the environment and 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 or produced using organic farming techniques and should be used with safe handling procedures and caution. 

      Examples of Mineral / Salt Treatments:

      It should be noted that though these mineral / salt treatments are moderately dangerous for humans and the environment, when used properly they can be a very effective odor-elimination solution and environmental or human health isn't at risk. 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.

      4. Bacteria Holding Tank Treatments

      Bacteria treatments are another very common type of holding tank treatment and there are multiple things bacteria do very well:

      1. Waste Break Down
      2. Odor Control
      3. Preventing Waste Build-Up / Residue 

      Bacteria are living organisms and when added to your holding tank, they multiply exponentially over time. Each bacteria creates their own enzymes to break down the solid waste into bite-sized 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, they also create noxious gases as a byproduct (hydrogen sulfide gas, methane etc.) during the waste breakdown process. This is why it smells when you pass gas. It is also why your holding tank smells.

      Aerobic bacteria, however, require oxygen to survive and are the main component of high-quality bacteria-based holding treatments. These types of bacteria do not create noxious byproducts. They, instead, create carbon dioxide and water as byproducts. So, as they break down the solid waste, they 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. However, 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 but hopefully now you are a little more clear on how they work.

      Below we have outlined our opinions on these four different types of treatments. Surprise! We are biased! Hopefully you will see 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!


      Our Opinionated Take On Holding Tank Treatments


      Chemical / Formaldehyde

      Many years ago these 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 quite 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 haven’t ever smelled these products, it’s hard to explain how strong the fragrances actually are! Many claim that they are worse smelling than the actual toilet waste! 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 off, you’ll get to smell the over-powering smells of cancer, er, fragrance! Needless to say, you should 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 and 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 of this junk when you bought your RV! Throw it away and start using a better working, healthier, safer alternative!



      Enzyme treatments are a great solution for quickly breaking down waste but unfortunately do nothing to eliminate odors – unless they’re packed full with odor-masking fragrances. Many people confuse enzymes and bacteria and 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 it down into smaller particles. And typically they work fast.

      Besides doing next to nothing to eliminate odors, enzymes have limitations. For one, unlike bacteria, they don’t grow in size. Simply put, if you pour 1 million enzymes into your black water tank you will still have 1 million enzymes in 20 years, whereas bacteria will continuously grow in count as they populate or “colonize” inside your tank.

      Another problem with enzymes is that they can be potentially dangerous to people who are allergic to enzymes so 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, though enzymes are very fast working and can perform well in extreme temps (very high or low) they don’t necessarily eliminate waste. They simply make it smaller. Only bacteria have the ability to completely eliminate (biodegrade) waste until it is completely gone.


      Mineral / Salt

      One of the more popular methods of odor reduction today is using minerals and salts to chemically neutralize odors. On the one hand these 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 very 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 my knowledge, none of the waste water treatments that claim they are “Organic” have ever gone through this testing.

      Being blunt – 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 because they have green washed  their products by claiming to be “Organic”. User beware!


      Full Disclosure:

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

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

      Frankly, 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 aren’t.

      So, we set out to make a version that was self-contained in a drop-in pod so 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.

      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 you are routinely in situations (like high heat or dry camping) where odors are making your RV experience unbearable and unenjoyable, then you may be willing to overlook some of your green / health concerns and use Tank Odor Eliminator. The choice is yours and we will never try to make erroneously claims of this product being “Organic”. We want you to be informed of the products you’re choosing to use and we intend to be completely transparent and honest in these matters.



      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!

      Bacteria have really gotten a bad rap for the last hundred-or-so years, but actually, 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. Heck, 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. Without them we would probably couldn’t survive. Also, truth be told, there are some that are dangerous.

      Luckily for you, the bacteria that are generally found in tank treatments are “non-pathogenic” bacteria – at least they are in RV Digest-It! That means they’re TOTALLY safe and healthy! Just like the probiotic you take every morning.


      So, why are bacteria so great for holding tanks?

      We're glad you asked!

      Bacteria are a natural waste digester and odor eliminator. Bacteria are living organisms (just like you and me!) and they require two things to thrive, food and water. Both of these are found in your holding tanks as they feast on the items that most people would think are absolutely disgusting.

      Here's how it works:

      When you add a bacteria 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 you never get tank clogs or backups. One problem down!

      The other thing high quality bacteria products do is they replace the naturally occurring anaerobic bacteria with aerobic bacteria. What does this mean? Odor elimination! As anaerobic bacteria from your stomach break down waste they let off hydrogen sulfide gas (that nasty methane smell you get in your toilet tanks and when you pass gas) – these smell makers 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. And it’s done by completely safe, natural occurring bacteria! It’s a beautiful thing, isn’t it?

      Remember how we mentioned at the beginning of this post that it was crucial to do both – eliminate odors and digest waste? Well, bacteria is the only solution that will do both.

      Key Take Away Time! Bacteria are the only treatment option that do both, waste digestion and odor elimination. And they are the only option that are completely safe and natural! What more are you looking for?!

      Something of importance to note: bacteria create enzymes. So, if you are using a bacteria product you are also getting an enzyme product! Bacteria’s only goal in life is to eat waste but unfortunately, they have very small mouths so they need to break down the waste into smaller, bite sized pieces before they can eat and digest the waste. To do this they create enzymes that take the big pieces and break them down into smaller pieces.

      Another incredible part of bacteria is that they multiply and grow as they “colonize” the inside of your holding tanks. That means that as they digest the waste they keep growing in number and each one of them is producing more and more enzymes. 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.

      Choosing the right RV toilet chemical for your camping needs

      Quality Matters!

      The quality of the bacteria is incredibly important. You need to have high quality bacteria, in the right strains, with the correct formulations to work optimally. Many bacteria products available today consist of cheap, watered down formulas with completely wrong bacteria strains – so don’t simply assume that just because a product contains bacteria that it’s going to work! Luckily for you, RV Digest-It contains billion of the highest quality, best formulated strains of bacteria in each and every treatment. Shameless plug!

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



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

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

      Without sounding like Chicken Little - Be very cautious about what tank treatments you use. You don’t realize how dangerous or detrimental they can be! Even if you don’t care about 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 past-time and it’s entirely possible to enjoy it without resorting to over-priced, dangerous, ineffective products. Choose your products wisely and you’ll never regret it!

      If you have questions on tank treatments or need further clarification, we’re always here to help! Drop us an email!

      Happy Camping!


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