How to Clean RV Holding Tanks

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Recreational vehicles generally have three holding tanks. "Black water" tanks hold waste from the toilet. Water from the kitchen sink, bathroom sink and shower drains into the "gray water" tank. "White water" tanks hold fresh water that's safe for drinking. Tanks need to be kept clean to prevent buildup and unpleasant odors. The basic cleaning principles are the same for all RVs. Read your user's manual for procedures specific to your rig.

Items you will need

  • Household bleach

  • Baking soda

  • Rinse wand

  • Holding-tank solution

Step 1

Sanitize the white water tank by draining it and then filling it halfway. Add 1/4 cup household bleach for every 15 gallons of capacity in your tank. Run cold water through all of the faucets, then run hot water to get the bleach into the hot water tank.

Step 2

Let the water stand for six hours, then drain the system. Add 1/4 cup baking soda to a gallon of water, and pour it into the white-water tank. Fill the tank, then open all the faucets to remove any traces of bleach. Drain the tank, then fill it with fresh water.

Step 3

Allow the black water tank to fill two-thirds full to prevent solids from accumulating under the toilet. Follow your RV manufacturer's instructions for emptying the black water tank at a campground or truck stop dump station.

Step 4

Use a rinse wand. The wand attaches to a hose and enters the black water tank through the toilet. Clean water rinses the tank as it is flushed through the wand, preventing waste from building up on the bottom of the tank.

Step 5

Treat the black water tank with a holding tank solution added to enough water to cover the bottom of the tank. After adding the solution, use your tank as you normally would.

Step 6

Use the gray water tank to help clean out the drain hose when emptying the black water tank. Close the water valve the evening before you break camp. In the morning, empty the black water tank first, then the gray water tank. The gray water will clean out the drain hose.


  • Don't let a lot of solid matter go down the kitchen sink. It can clog the system.


  • Install a water filter on the fresh water intake to keep sediment out of your system.
  • Some experienced RV owners recommend using a solution of two cups of water softener in a gallon of hot water in both the gray water and black water tanks.
  • Gray water tanks don't usually need treatment, but if they begin to stink, use the same chemical solution in the gray water tank that you use in the black water tank.