Simplify Your RV Waste Management: How to Combine RV Black and Gray Water Tanks


Managing wastewater is a vital aspect of RV ownership, and understanding how to combine RV black and gray water tanks can make this process more efficient and convenient. By merging these two tanks, RVers can extend their time off-grid and streamline their waste disposal procedures. In this guide, we’ll explore the reasons for combining your black and gray water tanks and provide step-by-step instructions on how to do it safely and effectively.

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Why Combine RV Black and Gray Water Tanks?

  1. Extend Off-Grid Stay: Combining black and gray water tanks increases your wastewater storage capacity, allowing for longer off-grid stays without the need for frequent tank dumps.
  2. Convenience: Merging the tanks simplifies the waste management process by reducing the number of tank dumps and making disposal more efficient.
  3. Sustainability: A combined tank system can reduce the environmental impact by minimizing the number of times you need to empty and treat wastewater.

Step-by-Step Guide: Combining RV Black and Gray Water Tanks

Step 1: Safety Precautions

Before you start, ensure that your RV is parked on a level surface and that both the black and gray water tanks are empty. Also, put on gloves and have all the necessary tools and equipment ready.

Step 2: Locate the Tanks

Identify the black and gray water tanks’ locations and access points in your RV. These are typically found underneath the RV, and there are valves and caps to control the flow of wastewater.

Step 3: Prepare the Hose

You’ll need a hose to connect the two tanks. Select a suitable hose that is clean, in good condition, and long enough to reach from the gray water tank outlet to the black water tank inlet.

Step 4: Open the Valves

Open the valve for the gray water tank and close the valve for the black water tank. This will allow the gray water to flow into the black water tank.

Step 5: Connect the Hose

Connect one end of the hose to the gray water tank outlet and the other end to the black water tank inlet. Ensure the hose is securely fastened to prevent leaks.

Step 6: Monitor the Process

As the gray water flows into the black water tank, keep an eye on the tank levels. Once the black water tank is nearly full, close the gray water tank valve to prevent overfilling.

Step 7: Mix and Dilute

To help break down solid waste in the black water tank, consider adding a black tank treatment product. Some RVers also add a few gallons of clean water to assist in diluting the contents.

Step 8: Empty the Combined Tank

When it’s time to empty the combined tank, open the valve for the black water tank and drain as usual at an appropriate waste disposal station. Ensure you follow local regulations for waste disposal.

Step 9: Rinse and Clean

After emptying the combined tank, use the built-in tank flushing system or a specialized wand to rinse and clean both tanks thoroughly.


Combining your RV black and gray water tanks is a practical solution for extending your off-grid adventures and simplifying waste management. By following these steps carefully, you can merge your tanks efficiently and safely, reducing the number of trips to the dump station and minimizing your environmental impact. Just remember to use the combined tank responsibly and follow proper sanitation and waste disposal practices to maintain a hygienic and hassle-free RV lifestyle.

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