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The Geo Method

January 10, 2019

Does The Geo Method Work On RV Black Water Holding Tanks What Are The Reviews Is It Safe To Use

Updated December 2019

Have you ever wondered what The Geo Method is? In this article, we will cover all the aspects of The Geo Method: how it works, its pros and cons, how waste digestion and odor elimination fit into the picture, and our recommendations. 

What is The Geo Method?

Created in the 80's by Charles Bruni, The Geo Method uses a combination of powdered Calgon (i.e., water softener), laundry detergent (i.e., soap/surfactant), plenty of water, and often bleach or chlorine (to attempt to control odor). Through his extensive experience as an RVer, Bruni created  The Geo Method as a homemade system for treating your holding tanks that many people swear by and is widely believed to be an effective and cheap treatment method. 

First, what does it mean to maintain a holding tank? Bruni argued that maintaining a holding tank means keeping the tank sensors, walls, and base clear of debris. We don't disagree! However, we also believe that proper tank maintenance should go beyond just keeping the interior of the tank clean (covered more below).

At the core of the The Geo Method system is based off of the following concept: a washing machine’s interior is never dirty because soft water and detergent not only clean your clothes, but also the interior of the washing machine as well. The Geo Method simply applies this logic to RV holding tanks.

How Does The Geo Method Work?

Through the process of water softening (using Calgon), organic and inorganic waste are made to not stick to the walls of your holding tank. Additionally, laundry detergent or dish soap is used to penetrate any solid waste that may still get stuck to the walls or sensors in your RV and help rinse it away.

All in all, The Geo Method is a decent solution for cleaning the interior walls and sensors in your RV black water holding tank. In order to implement the Geo Method, follow these steps:

  1. Dump both of your holding tanks (black and gray).
  2. Dissolve 2 cups of water softener (Calgon) into 1 gallon of warm water. Again, do this for both your gray and black tank.
  3. Add 1 cup laundry/dish detergent to your holding tank.
  4. Add chlorine/bleach as needed to control odors. 

Pros and Cons Of The Geo Method.


  • The Geo Method works for many people. Using the method, they have been able to effectively rinse away solid waste from the interior of their RV black tank, leaving it free from residual debris.
  • When used correctly, The Geo Method can be an effective way to prevent misreading sensors.
  • The Geo Method is a safe alternative to treating your tank with caustic or dangerous chemicals (which we do not recommend!).
  • The ingredients used in The Geo Method are readily available and easy to find.


  • The Geo Method does very little to break down solid waste. If solid waste is not broken down, it can lead to clogs and backups.
  • The Geo Method does nothing to reduce foul tank odors.
  • The Geo Method will kill the beneficial bacteria inside your tank that are actively working to eliminate odors and digest waste.
  • If you are using it in conjunction with a holding tank treatment, The Geo Method may be negating the benefits of the treatment. You are essentially throwing your money down the drain!
  • The Geo Method isn't necessarily an effective treatment process for dry campers (boondockers).
  • The Geo Method is actually quite expensive when you consider the cost of ingredients over time.

With this information in mind, let's dig a little deeper into The Geo Method.

Understanding Water Softeners and Their Effect on Holding Tanks

Calcium and magnesium—minerals that are found in the water in your holding tank—can cling to your tank sensors, causing them to misread. Therefore, the process of water softening works by removing the calcium and magnesium from the water in your holding tank. 

This is a good thing in the context of the Geo Method!

However, this process can also make the water inside your tank uninhabitable for bacteria. This is because the ingredients in Powdered Calgon cause a chemical reaction with hard water that raises the water’s PH to levels. Higher PH levels kill off good bacteria. In addition, Powdered Calgon also creates sodium bicarbonate (i.e., baking soda) as a byproduct of the chemical reaction with hard water. All this can cause quite a headache for you! Without bacteria, which would normally digest solid waste, you will likely have issues with clogs and backups. 

In all honesty, many people don't fully understand that bacteria and enzymes are crucial to maintaining a clog and odor-free holding tank. We understand! That’s why we’re here! If you aren't familiar with this concept, you can easily learn more about how bacteria and enzymes help to digest waste. Once you see the bigger picture, you’ll be able to see more clearly how The Geo Method interferes with the breakdown of waste and the elimination of odors.

Will the Geo Method Kill the Beneficial Bacteria in my Tanks and Cause Problems?

A quick note on bacteria: anaerobic bacteria (which is already in your gut and is present in human waste), is much more resilient to chemicals and may often survive treatment with the The Geo Method. At first glance this sounds great! Unfortunately, though anaerobes are helpful in digesting solid waste, they also release methane and hydrogen sulfide gas, which creates that all-too-familiar sewer smell.

Unfortunately, aerobic bacteria (which do effectively break down solid waste and eliminate odors by releasing carbon dioxide and oxygen—the kind you really want in your tank) will likely die off in the high PH environment created by Calgon.

Simply put, with The Geo Method, you are reducing the chances that your solid waste will get adequately digested. Furthermore, if used as a regular treatment, it is likely that you will actually increase the ability of anaerobic bacteria to create strong toilet odors.

Dry Camping

If you are someone who boondocks or otherwise has issues keeping water in your tank, you will also likely have problems with odors and clogs. The fact is that the water used by The Geo Method is the only thing keeping odors under control. Needless to say, water alone is not a foolproof solution to preventing nasty odors! 

If you plan to use the The Geo Method while dry camping, here are your only viable options for using water as an odor control:

  1. Before you leave for a trip, add a buffer of 5 gallons of water (or more) to your holding tank. This allows your water reserves to stay ahead of a possible pyramid clog.
  2. Keep a few inches of water in your RV toilet to create a water barrier, blocking the smells from seeping into your RV (like you would find in your home toilet).

Even these steps can only do so much to reduce tank odors. When you're dry camping, the odors will build up, because, as many dry campers will say, even in the best-case scenario, you can still get odors. Water softener and soap simply can't cover all the bases.

Bleach and Chlorine in Your RV Holding Tanks

As we covered above, bacteria and enzymes are crucial to maintaining clog and odor free tanks. We have also discussed how Calgon can kill the beneficial bacteria. For people who use bacteria holding tank treatments, this is a major detractor to The Geo Method! 

Now we move into another problem: adding bleach or chlorine to your holding tank in order to eliminate odors. This is specifically prescribed by The Geo Method. 

The only problem is that bleach and chlorine are specially designed to kill bacteria! The logic here is simple: if you wish to keep the bacteria in your tank alive, you cannot use bleach and chlorine! 

Since we have discussed this already at length, we won't go into this any further. Needless to say, killing the bacteria in your tank is almost always a bad idea. While it may eliminate some of the odors, it is only a matter of time before you get a backup or compacted tank.


Many people who choose to use the Geo Method are able to do so affordably; however, based on what we have found, between Calgon and Tide laundry detergent, the ingredients come out to be roughly $3.68 per treatment. Moreover, this doesn't account for added bleach or chlorine. 

To put that in perspective, Unique’s RV Digest-It Holding Tank Treatment is only $0.87 per treatment (or lower if you use the larger sizes). Though The Geo Method feels inexpensive at first glance, it is actually one of the most expensive ways to treat your tanks if you use it regularly!

How Does Unique Camping + Marine Fit into the picture?

Unfortunately, due to increased PH levels, the process of softening water can and often will damage bacteria; therefore, many of our products aren't a great option to use in conjunction with The Geo Method. For many people, The Geo Method is effective for cleaning sensors and preventing waste build up on the inside of a holding tank. Consequently, occasionally using the The Geo Method can be a good way to prevent sensor issues. However, if  in your tank, you'll need to thoroughly rinse your tank after performing The Geo Method. After rinsing your tank, you should be able to resume bacterial treatments.

The Unique Method

Waste break down can become a monster of a problem very quickly if not handled properly, and The Geo Method probably isn't the best all-around solution. 

With that said, we would like to recommend an alternative treatment method that will solve both your waste breakdown issues and your odors: The Unique Method. If you follow The Unique Method, clogs, odors, and misreading sensors will become a thing of the past!

The Unique Method is a proven holding tank treatment process that we have meticulously developed over the years through in-depth conversations with campers of all types. Our process is easy to follow and will virtually eliminate all problematic tank odors, prevent clogs and pyramid plugs, and ensure that your tank sensors continue to read properly. With The Unique Method,  we've taken the confusion out of tank maintenance by developing a very simple yet robust program that is hands-down the most effective process available today.

Read in-depth about The Unique Method here!

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


In conclusion, The Geo Method may be a good solution for preventing sensor problems, and it can be used to successfully ensure that your tanks remain clean and free from residue. However, it is not a perfect nor complete solution to treating your RV holding tanks; indeed, it may present you with additional problems.

The Geo Method, in our opinion, is only one solution to a complex problem. Considering The Geo Method's inability to effectively break down solid waste, the complications that come with not having enough water to suppress odors while dry camping, the cost of the ingredients, and the inability of The Geo Method to eliminate odors, it is difficult for us to recommend this process as a regular tank treatment. Instead, as we covered above, we recommend The Unique Method

Of course, this is just our opinion—though it is well-researched and thought out. We would love to hear your thoughts on The Geo Method! If you have any questions, concerns, or comments, please feel free to reach out to us at We would love to answer your questions or chat with you about The Geo Method!

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