There are a wide variety of RV holding tank treatments available, from liquids to drop-in tabs, to powders.
In fact, we reviewed and compared the 5 best RV black tank treatments on the market today.
But, sometimes you just want to do-it-yourself. Maybe to save money, you have the supplies already lying around your house, or because certain treatments aren’t available to you.
Whatever your reason is, we’ll show you the best homemade RV holding tank treatment options and explore how these treatments can help clean and remove foul odors from your tanks.
Types of RV Holding Tanks
The typical RV has two to three holding tanks.
The black tank handles sewage water from the toilet while the grey tank—you may have more than one, depending on the size of your RV—holds dirty water from the kitchen sink or shower. The freshwater tank holds clean water for drinking, cooking, and bathing.
Grey and black RV holding tanks need regular cleaning and emptying to avoid substantial waste build-up, which can cause clogs and foul odors.
Tip: Empty your black tank when it’s at least two-thirds full. This will ensure that you have enough water in the tank to flush away solid waste to help keep your tanks clean. Learn more in our guide on how to clean out an RV black water tank.
The Best Homemade RV Holding Tank Treatment
After you’ve emptied your holding tanks, you should also treat them.
Here, we break down the best homemade RV holding tank treatment options that will keep your tanks clean, functional, and odor-free.
The Geo Method
As an RV enthusiast, Charles Bruni developed this homemade treatment for RV holding tanks in the 1980s. He intended it as a cost-effective method for keeping tank walls, sensors, and bases free of waste.
At its core, the Geo Method imitates the workings of a washing machine. Bruni argued that the interior of a washing machine never gets dirty because the detergent, bleach, and softener clean the washing machine interior while they clean clothes. He then applied this logic to the cleaning and treatment of RV holding tanks.
In the recipe below, Calgon, a water softener, ensures that organic and inorganic waste does not stick to the holding tank walls. At the same time, laundry detergent or dish soap penetrates any solid waste and dislodges it from the tank walls, rinsing it away without scrubbing. Bleach or chlorine acts as an odor controller.
This method is safe to use on both grey and black tanks.
The Geo Method uses a combination of core ingredients to clean and sanitize holding tanks:
- 2 cups powdered Calgon (water softener)
- 1 cup laundry detergent or dish soap (surfactant)
- 1 gallon of warm water
- Bleach or chlorine, as needed (odor control)
Cleaning Your Holding Tank with the Geo Method
To clean your tank using the Geo Method, first dump your holding tanks. Then dissolve 2 cups of Calgon into 1 gallon of warm water and add in 1 cup of laundry detergent or dish soap and chlorine or bleach as needed.
Keep in mind that if you don’t want to kill the beneficial bacteria in your tank, then you’ll need to leave out the bleach and chlorine. While these chemicals effectively eliminate odors, they will kill helpful bacteria, which, in turn, won’t be able to break down the solid waste.
Here’s an excellent video illustration of the Geo Method at work.
The Citric Acid Cleaning Bomb RV Holding Tank Treatment
It may seem a little odd (and unsafe) to use acid in your tanks. However, citric acid, a weak acid naturally occurring in citrus fruits, can safely treat your RV tanks as a powerful cleaning agent.
You can also find this common ingredient in commercial black water tank cleaners as it works well for removing calcium build-up in your holding tank.
So, how can you turn citric acid into one of the best homemade RV holding tank treatments? You include it in a homemade citric acid cleaning bomb using the simple ingredients and instructions below.
You’ll need the following components to make your homemade citric acid holding tank treatment:
- Mix the baking soda, borax, and citric acid in a gallon-sized Ziploc bag.
- Slowly add drops of water until the ingredients bind together.
- Pack the cleaning bombs tightly into silicone molds. You can use golf ball-sized ice cubes to help press them into the molds.
- Let them dry overnight.
- Once dry, pop the cleaning bombs out of molds and dry them for 1-2 days.
- Store in an airtight container until needed.
Tip: To make these bath bombs effective, use just enough water to make everything stick together. Too much water will change their consistency and make them less effective.
Storing the cleaning bombs in an airtight container prevents them from absorbing moisture and losing their cleaning properties.
How to Use Citric Acid Cleaning Bombs
After you have dumped your RV black water tank, pour a couple of gallons of water down the toilet and drop one of these cleaning bombs into your RV toilet.
Let the bomb fizz inside the toilet water, and then flush your toilet. Ensure that you have a sufficient amount of water in your black water tank to allow for thorough cleaning.
If you can, use these cleaning bombs right before you travel, as the driving will move the cleaning bombs around the tank, which improves the cleaning action. These gentle bombs can also treat grey tanks.
The Unique Method
The Unique Method is more of a DIY process than a treatment, but I really believe it’s worth noting here. Why? Because whether you plan on using a homemade RV holding tank treatment or a store-bought one, the process with which you use them is just as important as the treatment itself.
This method prevents clogs and plugs effectively and eliminates problematic tank odors in a non-caustic cleaning action. It does so by using a combination of good aerobic bacteria and enzyme products mixed with some best practices.
The Unique Method advocates for the use of adequate amounts of water to eliminate odors and dislodge liquefied waste. This method encourages RV owners to dump holding tanks more often and use extra water when cleaning and draining the tanks to compensate for odor production. These measures allow aerobic bacteria to thrive and digest solid waste, as they have enough water to survive in these environments.
This method recommends the use of extra water when camping in hot weather. More water keeps your RV holding tanks cool, creating an environment conducive to good bacteria.
Using the Unique Method to Keep Your RV Holding Tanks Clean
To implement the Unique Method, you should:
- Always fill your toilet bowl with water before using the toilet to help waste flow effectively through the sewer system.
- Always keep the black tank valve closed, except when dumping the tank.
- Always treat holding tanks with a high-quality bacteria and enzyme tank treatment, like RV Digest-It, every time you dump your tanks.
- Flush your holding tanks with a built-in tank-rinse, tank-flusher, or wand for 20-30 minutes every 3-5 dumps to flush out compacted waste manually.
- Keep adequate water in the RV toilet bowl to minimize foul smells in your RV.
- Keep holding tank temperatures below 85°F as much as possible. If you suspect that the temperature inside your tank has exceeded 85°F, use more water with each toilet flush to cool the tank interior.
- Minimize cleaning your toilets with caustic chemicals like chlorine or bleach and use only mild RV toilet cleaners that won’t kill the aerobic bacteria.
- Try to dump your holding tanks every 4-5 days for the best odor control.
- Use ample amounts of water when flushing the RV toilet to hydrate the aerobic bacteria inside the holding tank. The water allows them to break down the solid waste and suppress odors.
- Deep clean your black tank biannually to flush out the system, remove waste and debris from the walls, base, and sensors, and lubricate your seals and valves.
Which RV Holding Tank Treatment Is The Best?
There are pros and cons to each holding tank treatment or process above, so it’s really a matter of choosing the one that best fits your unique needs, camping style, budget, and so on.
The Geo Method works really well if you wish to prevent sensor problems and keep your holding tanks free from residue. However, this method does not suit dry camping, as you’ll need plenty of water to implement it. It also does not eliminate odors very well, especially when you opt to omit chlorine or bleach as an ingredient.
Citric cleaning bombs works best as an all-around maintenance method that you can occasionally use as a preventative measure. They particularly shine when it comes to eliminating foul odors and removing any calcium build-up in your tanks.
The Unique Method, which keeps tank sensors working and eliminates clogs and build-up without the need for caustic chemicals like bleach or chlorine, does require an enzyme product like RV Digest-It (so, it’s technically not a homemade treatment), but the process has been refined over the years and has been proven to be one of, if not THE most effective way to keep your holding tanks clean and odor-free. Plus, RV Digest-It is an all-natural product that actually comes out cheaper per use than any of the other homemade treatments mentioned.
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