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What Is The Best Holding Tank Treatment?

What Is The Best Holding Tank Treatment?

We get asked this all the time and of course we’re going to say that we believe RV Digest-It is! Come on, what did you expect us to say?

But seriously, besides shamelessly self-promoting RV Digest-It, let’s talk briefly about:

The unfortunate truth is some of the products that are available at your local RV parts store are downright bad for your RV, your health, and the environment, so avoiding these should be priority number one. Beyond choosing a safe treatment, you'll want to consider how effective it is a digesting solid waste, eliminating tank odors, and maintaining sensor probes and seals.

Knowing Your Terms

Before we jump into this, you should know, there are a lot of terms people use when discussing tank treatments - tank additives, holding tank treatments, toilet treatments, waste digesters, toilet odor eliminators, RV toilet chemicals, RV septic treatments, and camper toilet treatments just to name a few. Boiled down, they are essentially getting to the same problem – waste water maintenance.


Waste Water Systems

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.

When water and waste goes 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 be immediately dumped into the sewer. The same goes for your Black Water only this is the water and waste that comes from your toilets.

Diagram Showing how grey and black tanks flow to a valve

So, before we go any further, it’s important to remember that the two goals of a waste treatment is to breakdown waste and eliminate odors.

This might sound obvious to you but many people don’t realize that these are the reasons why we treat our tanks. Many think it’s only to remove odors OR they erroneously believe that motorhomes just 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 cleaner should do both, effectively: liquefy waste and eliminate odors.


The last thing before we jump into discussing the different types of treatments – 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!

So, let’s jump in!


Understanding The Different Types Of Treatments

Holding tank treatments come in four major variations

There are other types of treatments, but the overwhelming majority of the products available fall into one of these camps and you can find a quick comparison chart here for your reference.


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!


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 bearer of bad news 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 –  it is 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 Sulfate Monohydrate (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've saved the best for last! Bacteria!

Now before you say to yourself, “Ew! Did they 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 me 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, we even take probiotics, eat yogurt, and drink bacteria (Kombucha) to make sure our 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.



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 the 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.


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 you and I would think are absolutely disgusting.

Here's how it works:

When you add a bacteria product to your holding tank the bacteria began 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.


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 I 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!

We have a comparison chart to visually help you choose the right treatment type, here.

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

Happy Camping!