Black water tank will not drain

Sometimes it may only take you a few minutes to find the cut out disk and remove it instead of heading to the delaer and waiting for them to repair your issue.

Txcoachie wrote:
Thanks for all the advice.

Yes, this is a new trailer. I am going to try a back flush tomorrow. I have closed my gray tank tonight. So after the back flush I will run the gray through.

If it is new, I think I would also take back to dealer and let them fix the issue. Warranty should cover this.

Apparently 'tis the season for sensor questions.

We had the same issue with a brand new RV we rented in British Columbia. Tank showed full (on the gauges), and when empty valve was opened a little bit of liquid came off. I was so frustrated i looked with a flashlight on the dumping end with the black valve opened (now seems a very stupid thing to do):E. This is how i noticed the cutout disk blocking the orifice. I closed the valve, added more water, traveled to the next campground where i was lucky enough after dumping the black tank to find the cutout disc stuck perpendicular to orifice. It was very easy to be pulled out with a gloved hand.
I hope this will not happen to my new TT as it would be impossible to remove a cutout disc due to the length of drain i have.

New trailer.........been in it about 2 months.

Are you living in it?
Do you leave black tank drain valve closed until time to dump?

Level monitoring panel indicators are junk.

When toilet 'burps' time to dump black tank
When sink/shower drain slower than usual..time to dump grey tank

Fill tank up with water until you see it via toilet. Then open dump valve and check flow. A 'clear adapter' on end of drain line (sewer hose connects to it) will allow you to see how stuff is flowing and when tank rinses fairly clean.

If when draining it flows well but quickly slows down---could have a cut-out disc left in tank. (Installer cuts openings for drain/vent lines----disc falls in tank and doesn't get removed) Disc gets sucked down to drain and blocks it.

Hopefully that is not the case.....or the poop pyramid.

Liquid to stuff ratio.....low ratio causes problems/high ratio cures problems

First, don't rely on the tank readings. They are notoriously bad and just about always indicate inaccurate levels.

Turn off the water supply and look down into the black tank to see how much "solid stuff" is in there. If it's been well flushed after each dump, you should be able to see the black bottom of the tank as it left the factory.

If you don't have a built-in tank flusher, a clear elbow with back flush attachment like the Valterra one may work. There's also a wand you can stick down into the tank. With the water on, you can stand at the toilet and open the valve to let water into the tank. Try and put as much water in as you can so you get a good rush of water to help flush stuff out. May take 5+ minutes depending on how full the tank is.

If still not much success, the next line of attack is chemicals. There are RV black tank treatments available to help break up the solids and crud. Failing that, liquid drano will work as long as you use the type that does not attack metal and you don't flush it into an on-site septic disposal system (extremely important). Our owner's manual says to use liquid drano.

Once you finally get the tank cleaned, it is recommended that you put 4-5 gallons of water in the tank after each dump and flush and use at the campground. When you use the toilet, don't skimp on water when flushing, thinking that you are extending the time before the next dump. Insufficient water is asking for a plugged up tank.

Finally, you *could* buy a "Tornado" tank rinser however you need access to the tank and since you have an enclosed underbelly, it would not be an easy task. Tornado rinser You *could* also install Horst Miracle probes which are a lot more reliable than the standard button OEM ones, however, there's the same issue of access to the tanks. Horst Miracle probes There are various chemical treatments you can put in the tank before each use of the tank. Some say they don't work that well and some swear by them. I think "Happy Camper" is one recommended by many. We've tried the ice trick without success. The "Geo method" reportedly works well (just google it).

Remember, lots of water is the key to prevention of this common problem. ;)

I fill mine with water, water softener, and a bit of laundry detergent. This seems to make whatever is sticking to the sensors work itself loose.

Thanks for all the advice.

Yes, this is a new trailer. I am going to try a back flush tomorrow. I have closed my gray tank tonight. So after the back flush I will run the gray through.

Folks have suggested adding a bag of ice via the toilet,some water, and drive around a bit to loosen and break things up.

If this is a new TT you may have some debris from the build of the unit in the black water tank.
If this is an usd TT the previous owner may of not flushed the black tank enouh and now you have dried poop to deal with.
First of all do not rely on the black tank sensors they are unreliable.
Secondly have you filled the black tank all the way up, until you see water just below the toilet flap? By doin this you then will know it is full and when you open the drain valve you can se how much actually comes out.