Gray Tank Guidelines

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The Unique Method offers a well-calculated mix of healthy care habits that will improve the condition of your holding tanks no matter what kind of treatment product you decide to use, the type of camping you’re doing, or what kind of weather arises. In this section, we’ll examine the actual steps for maintaining trouble-free black water tanks. We have provided a brief amount of detail in the steps below, but will be discussing some of these details in more depth in later articles. Since we recommend using a high-quality treatment product with the Unique Method and our products were designed with The Unique Method in mind, we will be using Unique Camping + Marine products as examples while walking through the steps. The best way to get the most success out of using the method is to combine it with the products for which it was created. Follow the guidelines below as closely as possible, and you will easily avoid clogs, odors, and misreading sensors.

Note: RVers with Class B RVs or others with smaller sized holding tanks can still apply our recommendations, with adjustments for a smaller tank.

  1. Use your gray tank valve correctly depending on how you’re camping.
    • For hook-up campers, leave your gray tank valve open with a P Trap in the wastewater hose to create a water barrier, closing off foul odors from the sewer hook-up. If you are effectively wiping your dishes before washing, you should never have any solid food waste getting inside your gray tank; therefore, leaving your gray tank valve open when on hookups should pose no clog issues. We recommend closing your gray tank the night before you dump your black tank and using the collected gray water to rinse your wastewater hose after you dump.
    • For dry campers and boondockers, keep your gray tank valve closed and perform a deep clean using Dawn Ultra dish soap the night before you return home from camping. Keeping this valve closed is important because most national forests and dispersed campsites prohibit open dumping (allowing ANY wastewater to freely drain onto the ground). While in use, treat your gray tanks with a high-quality bacteria and enzyme treatment. We recommend RV Digest-It as it has been specifically created with The Unique Method in mind.

      Note: For a more detailed description of how to use RV holding tank valves correctly, refer to The Definitive Guide to Using Your RV Wastewater Valves.

  2. Minimize the amount of grease and debris that goes down your sinks and showers.

    Wiping your dishes before washing is great, but some amount of residual grease still flows down the drain; soaps, shampoos, and other personal care products will also add a bit of grease. Grease is the reason odors can develop inside your gray tank(s) and is the primary cause of misreading sensors in gray tanks. When leaving your gray tank(s) valve closed, greasy water sits idle and clings to the walls and sensors as the water level rises. Food debris not wiped away from dishes before washing can lead to clogs in the tank(s) as well.

  3. Regularly perform a deep clean on your gray/galley tank(s), using a strong grease-eating cleaner; refer to the Deep Cleaning RV Wastewater Holding Tanks guide for more details.
    • For dry campers/boondockers, it’s best to do a deep clean of your gray tank(s) on the last night of each trip before you head back home (and you don’t have to dump first!).
    • For hook-up campers, we recommend preventatively deep cleaning your gray tank(s) once every 5-10 dumps. If you start seeing sensors acting strange, it’s probably time to do a deep clean. Cleaning gray tanks is easy and inexpensive, so do it often.
  4. Use a high-quality grease-eating dish soap to wash your dishes. 

    We specifically recommend Dawn Ultra over the cheaper options because it is a great grease-eater and will not leave soap residue in the tank that will only add to potential problems.

  5. Use a high-quality bacteria and enzyme tank treatment (when the valve is closed).

    While we recommend using Dawn Ultra dish soap to clean your dishes and deep clean your gray tank, there are things like food debris that Dawn Ultra cannot address; a tank treatment like Unique RV Digest-It will begin breaking down any food debris that is present. Only use bacterial tank treatments in your gray tank when dry camping/boondocking where you must keep your valve closed; no tank treatment is necessary when you keep your gray valve open on hook-ups.

  6. Avoid cleaning your sinks, tub, or showers with chemical or antibacterial cleaners.

    Using these types of cleaners will kill the beneficial bacteria inside your tanks and counteract the benefits you gain from using bacteria and enzyme treatments. They can also damage the rubber components of the toilet bowl.

  7. Always empty your gray/galley tanks before storing your RV.

    Gray tanks with dirty water left in them long term will become coated with grease and create sensor and odor issues when you start using it the following season.

We invite you to view the videos about The Unique Method for the different types of RVing


Full Hook-Up Campers

Full Time Campers

Dry Campers

The next article will begin to dive deeper into the reasons why we recommend many of these guidelines.

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