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How Do Enzyme Holding Tank Treatments Work In RVs?

January 15, 2019

How Do Enzyme Toilet Treatment Chemicals Work In An RV, Motorhome, of Fifth Wheel

Updated Dec 2019

Nowadays, there are more and more people looking for safer, natural ways to treat their RV toilets and black water tanks. Thankfully, for the most part, the days of formaldehyde-based treatments and chemical treatments are behind us.

In terms of proper black water habits in your motorhome, trailer, or fifth wheel, the top holding tank issues have always been and probably always will be avoiding odors and clogs. Savvy RVers understand that the best way to safely control odors and prevent clogs is to use bacteria-based and enzyme-based products. All the same, what most people don't know is that there is a huge difference between bacteria products and enzyme products!

In this article, we’ll clear the air and outline exactly what enzyme-based RV chemicals do in a holding tank—their strengths, weaknesses, our recommendations, and how they are very different from bacteria-based RV treatments. 

Enzymes and Bacteria

Contrary to popular belief, enzymes are not bacteria! However, bacteria and enzymes are intimately linked, because bacteria create enzymes.

When bacteria are present inside your holding tank, their only purpose in life is to eat and survive (they are living organisms after all!). Different bacteria eat different things, and the types of bacteria found in high-quality holding tank treatments are especially heavy eaters. This means that they will eat all the things that cause clogs and odors in your tank (e.g., toilet paper, human waste, bad bacteria, etc). 

Unfortunately, bacteria have fairly small mouths, which means that they can't eat large compounds. So, to make these large compounds smaller, they shed enzymes!

Enzymes are simply non-living proteins that break larger things down into smaller things. After the enzymes have broken down the larger compounds, the bacteria can eat these smaller pieces of waste, digest them, and exhaust nothing but carbon dioxide and water (if you're using good aerobic bacteria, like what we put in our products). In other words, bacteria create enzymes to break down larger pieces of waste so that the bacteria can keep on eating!

Because enzymes are capable of breaking down solid waste, they are often confused with bacteria. However, bacteria and enzymes are fundamentally different in the following way:

  • Bacteria are living organisms that break down waste (using the enzymes they create) and completely consume it.
  • Enzymes are non-living proteins produced by bacteria to break down waste and other compounds. They don't consume the waste; they just make it smaller.

Important note: The type of bacteria you use in your holding tank—including what these particular bacteria need to survive and multiply—will dictate what type of enzymes are created. In other words, if you don't use the right type of bacteria, you won't end up with the right enzymes to break down the waste. This is why poor quality treatments work poorly. Poor quality treatments don't introduce the right type of bacteria (for bacterial treatments) or enzymes (for enzyme treatments); therefore, these treatments don't effectively break down waste. The fact is that not all treatments are created equal. You need treatments that include the right bacteria or enzymes to digest the specific compounds inside your tank. Just because a holding tank treatment has bacteria/enzymes, doesn't mean it's the right types, strains, or quality. For that reason, we recommend RV Digest-It

Pros and Cons of Enzymes

It has become popular—especially within the RV industry—to produce and sell enzyme-based holding tank treatments. However, there are some pitfalls to enzyme treatments of which the average consumer should be aware. 


  • Enzyme treatments are a completely natural way to break down waste. They are completely free of hazardous or caustic chemicals. 
  • Extra-cellular enzymes (those that are secreted by bacteria and exist outside the cells of the bacteria) often start working very quickly to break down larger pieces of waste.


  • Because they do not digest waste, enzymes do nothing to control RV holding tank odors. Instead, enzymes simply break waste into smaller pieces.  
  • Enzymes cannot multiply. Because they are non-living proteins, enzymes cannot reproduce, so you are essentially stuck with the amount you add.
  • Certain enzymes can be dangerous if inhaled.

Enzymes and RV Tank Treatment

As mentioned above, the major problem with many enzyme-based RV holding tank treatments is that they only offer you a limited number of enzymes at a time. For example, if you put 1000 enzymes into your RVs holding tank tonight, by next week, you would still have 1000 enzymes. On the other hand, if you used bacteria treatments, the bacteria would begin to multiply. Clearly, this is a significant downside to enzyme treatments. 

Furthermore, enzymes can’t consume any of the waste that they break down—only bacteria can. Herein lies the reason you can still get odors when only using enzyme-based treatments. As stated before, enzymes only break waste into smaller pieces, and if there are no bacteria in your tank to eat these smaller pieces of waste, then you will experience nasty odors. 

We have written a piece to help you learn more about odors here.

To be completely fair, enzymes will often break down waste in your black water tank very quickly and will work in high temperatures without slowing down at all. Nevertheless, without bacteria to help digest the waste, enzymes will still have no effect on the odors coming from your RV holding tanks. Therefore, enzymes can be great for clogs, but they are bad for odors. 

Moreover, without the help of bacteria, it is even possible for waste to clump back together after it has been broken down by enzymes. As a result, when you use enzyme treatments, it’s important to dump often to avoid clogs building up all over again. Obviously, this is not ideal!

The Dangers of Enzymes

Because enzymes are proteins, there is always the risk of an allergic reaction if the enzymes are inhaled. Both powdered and liquid form enzymes can become airborne. Consequently, you could develop an adverse immune response to the dust, causing anaphylactic shock or other allergic reactions if you ever come into contact with it again. This is much less of a problem if the enzymes are in a liquid form. To be fair, most producers of enzyme toilet treatments understand that there are some dangers to enzymes, which is why these products are normally in either a thick liquid solution (like Dawn dish soap) or in a drop-in pouch. 


As we discovered above, there are a few benefits to using enzyme based RV tank treatments:

  1. Enzymes work naturally without danger to the environment.
  2. Enzymes start working quickly to break down waste.

All the same, enzymes do not help with odors in any way, because they cannot consume the waste that they break down. Enzymes also cannot multiply on their own to continue to help break down waste in your RV holding tank. Furthermore, when in a dust/powder form, it has been found that enzymes can trigger an immune response and cause allergic reactions.

What you use inside your holding tank is ultimately your choice. We hope this article has helped you to better understand RV enzyme treatments. Hopefully you can now make a more informed decision about what products you add to your RV waste water system. If you have any further questions or concerns about this topic, please don’t hesitate to contact us at support@uniquemm.com. We’re always here to help!

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