Cleaning Holding Tanks
A new black water tank on a vintage trailer
To deep clean your holding tanks, you follow all of the steps listed below. Just make that before you open the gray water valve, you drain the black water tank completely.
Close the toilet lid to avoid breathing any toxic fumes. Cover the sink drains also.
Fill each tank 3/4 full with fresh water and two cups of liquid bleach. We use germicidal bleach.
Allow the mixture to sit in the tanks for 10 minutes, but no longer. Note that we typically pull the trailer to slosh around the solution so it cleans everything.
Drain the tank.
Fill it again with fresh water. Before you drain the tanks, this is a good time to check each tank, the drain lines, and the gate valves for leaks. If you find leaks, at least you have clean tanks to repair.
Continue to fill and drain until you see that the clear hose connector shows no debris, and the bleach smell has disappeared. This is very important to do because you need to make sure that there is no bleach left behind to damage your plumbing system.