Using Dawn Dish Soap in RV Black Tanks (Important Tips)

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Dawn dish soap is a versatile cleaning product renowned for its grease-cutting prowess and gentle impact on the environment.

And, increasingly, the ability to keep RV black tanks clean!

Below we cover how to use Dawn dish soap in RV black tanks, it’s pros and cons, important tips, and more!

What is Dawn Dish Soap?

dawn dish soap

Originally introduced by Procter & Gamble in 1973, it has since earned a reputation as a household staple, relied upon for an array of cleaning tasks, including, interestingly, RV black tanks.

Dawn’s formula, which includes surfactants and cleaning agents, is gentle on the skin (and your RVs plumbing) but tough on dirt and grime.

Importantly, Dawn is biodegradable, making it an attractive option for RV enthusiasts concerned with ecological impact.

Using Dawn Dish Soap in RV Black Tanks

As unorthodox as it might sound, Dawn dish soap can indeed be used to clean RV black tanks. When mixed with water, Dawn helps break down waste materials and clean the tank’s walls. This unconventional cleaning method is particularly helpful because Dawn dish soap is easily accessible, affordable, and effective.

And it’s as easy as squeezing a small amount down your toilet after each time you dump and refill the tank with water (always fill your tank about 10% full with water after dumping to avoid a poop pyramid).

Regular use of Dawn can reduce unpleasant odors and make emptying the tank a more manageable task.

Benefits of Using Dawn Dish Soap

In addition to its cleaning prowess, Dawn dish soap offers several other benefits when used in RV black tanks.

  • It’s effective at breaking down waste, preventing waste from clinging to the tank’s interior walls, and removing bad odors.
  • Its biodegradable formula is safe for the environment, so there are no worries when it comes time to dump your tanks.
  • Dawn is a very mild and non-corrosive soap, so it’s safe for your RVs plumbing system.
  • Compared to specialized RV tank cleaning products, Dawn is widely available and often more cost-effective.
  • It’s a very versatile cleaning agent that can also be used for dishes, removing stains, etc., which comes in handy when camping.

Potential Drawbacks

While there really are no drawbacks to using Dawn dish soap in a black tank, I would like to cover two potentially possible (but very unlikely) scenarios.

  1. Overuse can cause excessive suds, which might interfere with the sensors in your tank or lead to overflowing bubbles. That said, you would have to really overuse it and create a lot of agitation by excessive toilet flushing and repeatedly stopping and going while driving your RV to slosh the contents of the tank around.
  2. Although Dawn is very mild, it could potentially degrade the seals or gaskets in your black tank system over a long period of time. The thought for this comes from the popular advice to never use Dawn to wash your car, as it’s said to remove the wax and degrade rubber seals. While this is true for many types of soaps, I have yet to see proof that Dawn will degrade seals and gaskets. And with a ph of over 9, even for the powerful Dawn Platinum soap, I would say this is more of a myth than anything.

In other words, you can safely use Dawn dish soap in your black tank.

Note: If you’re one of the rare people that wax the inside of their toilet and black tank, you may need to reapply the wax more often if you regularly use Dawn.

Tips for Effective Use of Dawn Dish Soap in RVs

For the most effective use of Dawn dish soap in your RV’s black tank, follow these tips:

  • Use sparingly: Of course, you don’t want to empty an entire bottle into your black tank. A couple of long squeezes, or about a 1/2 cup, will be plenty.
  • Add after dumping: After you clean out your RV black water tank and add water back in, squirt a small amount of Dawn down your toilet. This will allow the soap to do its job between dumpings.

That’s it! It’s really a simple, hands-off black tank cleaner that just works.

Alternative Cleaning Options

While Dawn dish soap is a viable cleaning option for RV black tanks, it’s not the only solution.

Commercial black tank treatments, designed specifically for this task, are available and often contain enzymes or bacteria that break down waste.

Alternatively, homemade RV holding tank treatments, such as vinegar or baking soda, can also be used for black tank cleaning. Each of these alternatives has its own pros and cons and may be preferred depending on your specific needs and circumstances.


Can Dawn Dish Soap Damage My RV Black Tank?

Dawn dish soap is an extremely mild soap that will not cause any damage to an RV black tank. In fact, it’s beneficial because it will help keep the tank clean.

How Much Dawn Should I Use in My RV Black Tank?

There’s no recommended amount of Dawn soap to use in a black tank, as that’s not what it was designed for. But squeezing a small amount, about 1/2 cup, down your toilet and into the tank after dumping and refilling with water will allow the soap to do its job between dumpings.

Are There Alternatives to Using Dawn Dish Soap?

Yes, commercial RV black tank cleaners, homemade treatments like the GEO method or Citric Acid bombs, and other natural solutions like vinegar or baking soda can also be used.

1 thought on “Using Dawn Dish Soap in RV Black Tanks (Important Tips)”

  1. We have used the .5c Dawn .5c borax for the last 5 years. Prior to that we only used the “best” and costly tank treatment solution. Even using the “best” our sensors quit working. This caused us to buy all different kinds of sensor treatments. None worked- we were sensor less for a few years. Then I saw a YouTube (sorry can not remember who) about Dawn and borax. We started using it- it did take 1.5 seasons to get our sensors back in perfect order. They were somewhat intermittent by the end of the first season. With continued use of this mixture they stay in perfect condition. We will never go back to buying the commercial solutions.


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