“Our black tank in the RV is plugged up in the toilet tank. We bought one of those back-flushing devices and back washed the tank several times. We took a snake and ran it as far as it would go from the toilet side and still the tank will not drain. The snake seemed to just coil up. Is there something else we could try?”
– Randall, Phoenix, AZ

“Randall, the subject of those dreaded holding tank blockages surfaces from time to time. It’s further compounded when the holding tank is not positioned directly under the toilet. The optimum set-up finds the toilet drainpipe going straight down and into the holding tank without the use of elbows. Unfortunately some manufacturers, because of the floor plan design, are forced to use elbows to connect the toilet to the black water holding tank, which I’m guessing is the situation on your coach. Additionally, toilet tank blockages often occur when tank valves are left in the open position while in the campground allowing all the liquid to drain out leaving the solids behind to dry out and stick in the drain piping or coagulate at the tank outlet. Always keep the tank termination valves fully closed until each tank is above 3/4 full before evacuating. In most cases, an almost full tank will provide enough force to completely drain all the solids along with the liquids.”

“Perhaps it’s time to contact All-Pro Water Flow. Their specialty is hydro-cleaning holding tanks and drain assemblies by using very high water pressure and a special nozzle that allows cleaning of the entire tank interior. I recommend this procedure at least once a year anyway to keep the tank probes clean and to eliminate false readings on the monitor panel. Back-flushing with typical city water pressure will not adequately clean or clear stubborn blockages.”
– Gary Bunzer, The RV Doctor (RVDoctor.com)