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Best Homemade RV Holding Tank Treatment

Excluding only the tiniest of RVs, your vehicle likely has holding tanks. The holding tanks are what store the fresh and wastewater in your RV. Since they do carry waste, it is important to keep them clean to avoid unpleasant smells. 

Your RV will have three tanks: freshwater, grey, and black. They all need a degree of treatment and cleaning, even the freshwater tank, though it does not need a great deal of maintenance. When you need to clean your grey and black tanks, you will want to find the best homemade RV holding tank treatment. 

The best homemade RV holding tank treatment is a slurry of water softener, laundry detergent or dish soap, and bleach. Mix the ingredients together with water and flush them down the toilet after emptying your tanks. Some campers suggest doing this every time you dump the tanks, others only suggest it be done as needed. 

Best Homemade RV Holding Tank Treatment

There is nothing more unpleasant than the potential odors that can escape from your holding tanks, especially the black tank. The black tank is where waste from the toilet winds up. Even frequently dumping the contents of your tank won’t guarantee that it is completely clean. 


Once you’re hooked up to city water and have dumped your grey and black tanks, close your RV’s flush valve. To make this homemade RV holding tank treatment, find a large bucket (3-5 gallons) and begin to mix your materials: 

      • 2-3 cups of water softener. You can get this in liquid or powdered forms. 

      • 1-2 cups of laundry detergent. If you’d prefer, you can also use a dish soap that works well on built up grease and debris on dishes. 

      • Household bleach. A little goes a long way; you’ll only need a splash. If you are worried about bleach wreaking havoc on some of the seals of your RV’s toilet, you can skip this. 

      • Finally, at least one gallon of hot water per tank. 

    For best results, make this mixture twice: once for the grey, once for the black. This slurry makes the best homemade RV holding tank treatment. 

    Bleach is the component here that will remove odors from your holding tank. Detergent or dish soap will cut through any stuck debris and scrub the sides of the tank down. Water softener breaks down anything that might be stuck to the tank, like toilet paper. 

    These dislodging components are especially necessary, since it’s impossible to reach into the tank and scrub it. By clearing off the inner walls completely, you are keeping odors from lingering. 


    Dump the mixture down your toilet and flush. Give the treatment time to ‘soak’ off the insides of your holding tanks. You can leave this for a few days, or several days, depending on your timeframe. 

    Between repeating the steps for multiple soaks, dump your tanks. This will make sure you aren’t soaking the insides with the same nastiness you’re trying to remove. At the very least, you will need to dump the tank of cleaning solution before you call the process done. 

    For your black tanks, it may be wise to use extra laundry detergent or dishwashing liquid. Your grey tanks do not need the extra soap. They’re not as dirty, and because they’re sourced from the sink and shower, they already have some soap in them. 

    Do not use the method to clean the freshwater tank. The freshwater tank is what delivers your bathing and drinking water. The harsh chemical ingredients are not safe for consumption, and should not be introduced to the tank. 


    How Often Should You Use An RV Holding Tank Treatment? 

    How often you treat your RV holding tanks is a matter of necessity and preference. Some RV owners choose to do it every time they dump their water tanks. Doing so means it does not have to soak for as long, as there is not as much to soak off. 

    Others only do it when they feel it is needed, such as every few times they empty the tanks. If you are living full time in your RV, it might be best to do it every time you stop to clear out the tanks. This means you don’t have to keep it in as long, and your space will stay much cleaner. 

    Alternate Treatment Options 

    If after reading this you’ve decided that making a homemade holding tank treatment is not for you, just know there are Easy, Affordable, and effective products available.

    Disclaimer: I personally make my own, but from my research this is THE most liked product by RV’ers out there for holding tank treatment. If you do end up purchasing this, please let me know how you like it, compared to the DIY method that I use.  

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