black water tank clog

possible solution if its a turd blockage issue

get it about 1/3 full of water (leave sit overnight). In the morning add about 10 lbs of ice cubes. Go for a drive on some start / stop roads for 20 minutes or so.

The ice cubes will bounce around and knock anything stuck; then they melt and your golden for draining.

We have a cabinet right above our toilet and know a shampoo bottle has fallen in there. Luckily I heard it come through the drain tube when we were duping the tanks.

Just a suggestion if you know port a potty yard may want to call them I believe they have a honey dipper and they can suck out toilets just like to do for construction sites the hose should be small enough to get into the toilet to suck out the black tank save a lot of mess in case you open the valve and also have a failure

The device is called a Flush King.....as said you need a hose to connect in order to backflush your tank. The clear fitting allows you to see when water flushes out clear. Once tank is emptied, always keep some water in it.

Could have been pour maintenance by previous owners....let the turds get hard, and they just blocked the drain pipe? Could be some piece of the tank that was drilled for vents/fill pipe, that fell into tank, and not taken out when RV was built, and has finally gotten lodged in the drain.

In both cases, I'd see about getting one of those fittings for the discharge, that you can hook up a garden hose to, to flush the tank and line.....and then back-flush the water into the tank.

You may want to throw a towel over the toilet....just in case! :(

Good Luck:)