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Urine Is Not Water - Using Water In Your Holding Tank

March 03, 2020

Urine is not water - Using Water in Your Holding Tank vs. Thinking Urine is Enough

Key Points:

  • Although it contains water, urine’s chemical makeup makes it fundamentally different from water in terms of odor control. While clean water is odorless, urine is primed for odor creation. If you’re looking for an odor-free camping experience, urine is not your answer!
  • In The Unique Method, it's important that you use enough water to completely cover the solid waste in your holding tank. This creates a barrier to prevent odors from entering your RV. Aside from odors coming from the urine itself, it's unlikely that you will be able to use enough urine in your holding tank to completely cover your solid waste.
  • Furthermore, using urine as a substitute for water will diminish the effectiveness of a high-quality, bacterial-based holding tank treatment and create many issues when dumping your holding tank. 

At first glance, it seems really quite logical: if you need plenty of water in your RV’s holding tank to help facilitate the breakdown of waste and suppress odors, then plenty of urine ought to do the same thing, right? Actually, wrong! 

There are many reasons why urine is simply not a good substitute for water in your holding tank. Urine’s chemical makeup is fundamentally different than water and will cause odors, you will need more liquid in your tank than you can create in the form of urine, and using urine as a substitute for water will ultimately diminish the effectiveness of your high-quality holding tank treatment and create issues when it comes time to dump your tank. We’ll dive into each of these categories below! 

Check out our article on eliminating holding tank odors with beneficial bacteria!

Chemical Differences

As mentioned above, most people who think that urine is an adequate substitute for water are actually thinking somewhat logically. After all, urine contains water, so why can’t you just use urine instead of wasting water to fill up your holding tank? Well, the key word from the previous sentence is contains. While it's true that 91-96% of urine is made up of water, the composition of the other 4-9% completely changes its effectiveness in a holding tank.

Some substances that make up that 4-9% are salt (made up of sodium, potassium, and chloride), uric acid, and urea. We all know what salt is. If there is excess salt in our bodies, it will be excreted in our urine. Salt, however, is not the primary culprit for urine’s smelliness. It's uric acid and urea who are guilty of that.

Uric acid is a waste product created during the digestion of food, a result of urine metabolism. Urea is often expelled in the form of sweat, but it is also a major component of urine. Urea is a by-product of protein breakdown and is often broken down one step further into ammonia. And ammonia is where the majority of those nasty smells come from!

Beyond this, while urine is generally sterile, it can in some cases contain bacteria. In fact, according to Summit Medical Group, it is possible to have some bacteria in your urine and still be perfectly healthy. (Touch or click here to view the full article.)

When you combine ammonia with even trace amounts of bacteria, you’d better be ready for smells in your RV’s holding tank!

Urine Odors

With the chemical differences in mind, it’s easy to see why urine smells a whole lot worse than water. If you try to substitute urine for water, you’re essentially asking for RV holding tank odors. Moreover, when urine is allowed to metabolize inside your holding tank—combining with the bacteria in solid waste—it will smell even more! Because of that 4-9% that is not water, urine can be quite a smelly substance! The fact is that, if RV holding tank odor control is your goal, urine is not your answer!

How Much Liquid Do You Need to Use?

Beyond odors, however, there are some more practical things to consider if you’re contemplating substituting urine for water. A fundamental aspect of Unique’s treatment regiment—The Unique Method—is that you must use enough water to completely cover the solid waste in your tank. Covering solid waste with water creates a barrier between it and you, preventing odors from seeping up into your RV. 

The simple, frank fact is that you will not logically have enough urine to completely cover the solid waste in your holding tank (unless, of course, you’re downing several gallons of water per day [not a practical nor good idea]). In fact, we recommend holding down your flush pedal for at least 10 seconds every time you use your RV’s toilet. That’s a whole lot of water! It’s pretty unlikely that you’ll be able to deposit that much urine into your holding tank, even if you drink gallons per day!

Diminishing the Effectiveness of Holding Tank Treatments

Let’s assume, on the other hand, that you simply want to skip adding additional water to your tank. In other words, you don’t expect to use as much urine as you would water. No doubt, most of you who are considering using urine as a substitute for water are in this boat; you just don’t want to “waste” water by adding it to your tank. Even in this case, there are still more reasons why you should not do it!

If you follow The Unique Method (which you should!), a key step is to supplement your tank with a high-quality, bacterial-based RV holding tank treatment—like RV Digest-It. The bacteria in this product need plenty of water to hydrate them. If you use only urine (i.e., you simply choose not to add additional water), then the bacteria won’t have enough liquid in which to thrive. Without adequate water, these bacteria will not be able to most effectively break down waste. Not only that, but if the urine inside your tank does not completely cover the solid waste, the bacteria won’t even be able to get to the solid waste to break it down!

Fundamentally, if you use urine as a substitute for water, you’re essentially causing your high-quality holding tank treatment to work less effectively! And if the product can’t do its job, you’ve set yourself up for many future issues. 

Problems Dumping / Pyramid Plugs

If you substitute urine for water, one key issue that you will likely face in the future is problems dumping your tank. The Unique Method recommends that you dump your tanks every 3-5 days for optimum odor control. If, however, there is not enough liquid in your tank, you will almost invariably encounter clogs and backups when you try to dump your tank. Likely, you will discover a pyramid plug (a literal pyramid of poop that builds up inside your holding tank). A pyramid plug is the result of inadequate liquid and/or inadequate or ineffective bacteria colonies in your tank. As mentioned above, inadequate liquid and ineffective bacteria colonies often go hand in hand. 

Ultimately, if you use urine as a substitute for water, you will have inadequate liquid in your tank, which will impact the effectiveness of the bacteria, which will cause a pyramid plug, which will make dumping your tank a real hassle. In short, it isn’t worth it!

If you do happen to encounter a pyramid plug, don't worry! We've got you covered! Check out this guide on Unclogging An RV Toilet.


While it seems logical to save water by using just urine in your holding tank, urine is simply inferior to water. Using plenty of water will help prevent odors, cause the bacteria in your high-quality holding tank treatment to thrive, and make it way easier for you when it comes time to dump your tank. As always, we understand that this complicated topic and would love to answer any additional questions or concerns you may have. Even if you just have a comment, please feel free to reach out to us. We would love to help you!

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