Black water won't drain

Well there have been suggestions to add a bag of ice cubes to the tank and then drive around while the cubes theoretically mechanically bang into stuff in the tank. I don't know if it works or if that would be practical for you. The big gun in home sewers is Sulfuric Acid, but I would not want to be the one trying to dispose of that as it came out of the sewer hose.

Make sure plenty of water is in the tank to "move" the solids.

At this point, I would start looking fr a plumber with a video inspection camera. Are you sure there is anything actually in the tank to drain?? Seems like if drain valve is open, and a snake went in, if there was anything in the tank would have come out with the snake.

Water and Rid-X. Follow the instructions on the bottle, it worked for me.

You sent a fifteen foot serer snake up the drain from the valve and nothing? Could you see the snake moving in the black tank?If it weremine I would consider a sewer cap with ose fitting and send someot water up under mild pressure. Since it is your rig I would not reccomend this as it could cause line leak as those pipes are not meant to be pressuruzed. I guess I would reccomend the video camera idea. Let us know please

How do you know the tank is not draining. If you opened the dump valve and stuck a snake up the line past the valve I can almost 100% say the tank is draining/drained. There maybe solids still remaining. Do not trust the gauges. Close the valve and fill the tank through the toilet then open dump valve, connected to sewer of course.

Take a flashlight and look down the toilet what do you see?

Thanks for suggestions. The level is inside the toilet bowl so we know it's full. Will try ice and drive around in morning then I guess a plumber with a cam is the only thing left. Several friends camping with us and everyone is baffled after working on it all day.

Omer&Donna wrote:
We have snaked from toilet, from drain valve and from vent on roof and black tank will not drain. Valve is open since 15 foot snake went in. Many chemicals added to loosen clog but nothing is working. Any suggestions?

You also stated level is inside the toilet bowl.


Then I bet the valve is NOT opening. 15' foot of snake may have gone up the dump line but all it did is turn around/coil up when it got to the valve......otherwise tank would be draining if snake went into tank.

Can you SEE the valve ....or is it hidden inside an enclosed underbelly?
Cable operated drain valve?

Until you can physically verify that the drain valve is actually opening I would not waste time on 'ice' (too much liquid in tank and it doesn't really work to unclog a tank) or paying plumber $$ to run a camera.

Drain valve........NOT OPEN

Could be a plastic slug they cut out for the intake pipe, left in the tank floating to the gate.