RV Holding Tank Removal

I need to remove my black holding tank off of a 29-foot Class C motorhome with a slideout. How do you remove the RV plumping from tank? One RV person tried telling me you have to bust it out and replace it with a new tank. This make no sense to me. What can be done and how do you do it? Crawford O. (Dandridge, TN)

Crawford, I'm thinking your RV person is not familiar with the NFPA 1192, Standard for Recreation Vehicles. According to the code, all holding tanks must be removable. That alone, does not mean it’s an easy job. It simply requires manufacturers to make it possible for the tanks to be removed even if it means removing other components first. I go into detail about the procedures in my RV Owner’s Handbook. Unfortunately, it’s too much information to include in an email response, but be assured, it does not have to be busted out piece by piece. 

First verify that the tank actually requires a total replacement. Plastic holding tanks can be successfully welded if cracked. Only when completely destroyed or damaged beyond repair does it actually need to be replaced. I'd "remove and replace" only as a last resort. Here's the bottom line if it does have to come out...

The tank vent and toilet drain enter the holding tank from the top and the drain outlet exits at the lowest portion of the tank. In some cases, the vent can be cut with a hacksaw or disconnected from inside the cabinetry. The toilet simply unbolts from the floor flange, then the flange (which may be connected to the tank in a variety of ways), is simply removed from the top of the tank. The same for the drain outlet on the holding tank itself. It will ultimately terminate and connect with the other holding tank at a location near the left rear side of the coach. All termination valves are removable so you simply remove that pipe and valve associated with the tank in question and reverse the process for installation.

Wish I could provide more clear-cut instructions, but without seeing the actual installation it’s nigh impossible to respond fully. But I hope this little bit will help!