Forum Discussion

Heavy_Metal_Doc's avatar
Apr 12, 2014

More newbie questions - black tank flush system

We just started our TT life in the fall with the purchase of our first one.
I have read up a lot on the care and feeding of this new "animal", but am finding some minor issues in spite of all my attempted preparedness.

Today's adventure: using the black tank flusher for the first time.
I knew we had some solids piled up in the tank that need to get out of there, so I got situated to dump at home and connected the water hose to the outside and turned it on. I ran the flusher and watched the tank level come up past 2/3's before I went outside and pulled the handle to open the vale and drain. It seemed like very little of the solids came through. So I turned on the water and let it fill till it read full this time. Draining seemed like all liquid again.
Round 3: Filled to full and looked down through the toilet to see that it really was nowhere near full even though the indicator said it was. Turned the water back on while monitoring through the toilet and filled until the liquid level was just bellow the bottom of opening into the tank. I could see a lot more moving around inside the tank this time, but it still left a lot of solids laying in there when I drained it.

The first thing I realized during this process is that the flusher system sounds great in theory, but there is no outside way to monitor the level in the tank to know when you need to shut off the water / or open the drain. Maybe this doesn't matter if you are dealing with routine dumping, but for my situation of trying the loosen up stuck solids, it's a pain running in and out around teh TT to turn on and off the water. This leads to a change I'd like to make. I'm thinking of putting a valve for the flusher on / off inside under the bathroom sink so you don't need to run outside to shut it off.

Then I stepped back inside the TT again and realized I now had a sizable puddle of water growing across the bathroom floor. I quickly traced it back to the flusher system water line. There is some sort of check valve / vacuum breaker valve under the sink. It appears that water pressure is supposed to seal it shut and then let air in when you stop flushing to let the line drain. I leaks about on drop per second while the water pressure is on. It does not look like an item you can repair so, something to get replaced to fix the leak.


At the moment, I have filled the black tank completely, and am letting it sit to soak / loosen up solids overnight. I will see how much better it drains out tomorrow morning. If it does not clear out much better, then I am thinking I may need to go get one of the through the toilet wand type washers at this point.

Any advice is appreciated!

28 Replies

  • your description of your tank flusher/sprayer confuses me. my systems have all been external to the RV. sprayer mounts on side of black tank and hose stays outside to hook up or are you talking about that tiny wash down the toilet sprayer that some RVs have?
    re-reading your post leads me to believe that you don't have a black tank spraying system at all.
    bumpy
  • How do you know you have solids piled up in the tank? Are you seeing a pyramid like Old-Biscuit mentions or are you just generally concerned?

    If just concerned I would say don't worry about it. Just drain the tank, run the flusher for a while to refill it, then drain it again. Add a few gallons of water to the tank to keep things from drying out and put the trailer away. There's just no need to get the tank spotlessly cleaned.

    Now if you have a pyramid from too much use with not enough water then you're going to have to get it out. But personally I would just fill the tank with water and let it sit for a week or more and I'll bet that pile dissolves on it's own.
  • That's a new trailer.....2014 model

    So I take it you have done some No-Nos
    Either have left the back tank dump valve OPEN when using trailer
    Have dumped black tank after each use with very little water in it
    Have not added a couple gallons back into black tank after dumping so bottom stays wet
    Are not using a full toilet bowl (+) when flushing solids

    You have the dreaded 'poop pyramid'
    Your tank flusher is just a sprayer in top of tank to help rinse down the sidewalls and rinse out tank.
    It will NOT power flush the tank
    You will need to power flush with a stream nozzle on end of garden hose down thru toilet to blast the pyramid. Have dump valve open

    The RV Digest product does work.....but takes a while.
  • The fellow who I bought my TT from suggested the easiest way to clean out the black tank was to dump a couple bags of ice cubes down the toilet then go for a drive. The cubes will essentially sandblast all the******(literally) off the tank, and melt.
    Drain and you're done.

    Haven't tried it but I can't dispute the logic behind it.
  • It sounds like more water needs to be flushed into the tank from now on each time it's used to prevent the solids from being stuck in there.

    Meanwhile, back at the ranch, letting it sit full of water should loosen things up in a couple of days. There is the old ice cube trick. Fill the tank about 1/4 full, put a bunch of ice cubes down the toilet and go for a drive with lots of curves, corners, stopping and starting that will cause the ice cubes to slosh of the solids to wear them out of there - the ice cubes sort of serve as sandpaper. The more ice the better - several bags as it melts quickly.

    And leave some water in the tank (when it's not freezing out) to keep any left overs from drying out into solids.

    Bill
  • Why?

    What I might suggest is dump the tank, and then always make sure that you have about 5 gallons of water left in there. I was told that a dry tank and turn the soft "Left behinds" into a powdery sludge, that will become somewhat like mud, and difficult to wash away. By moving the trailer with 3-4 inches of water in heh tank, then that will break up the stuff, and the next time you drain it should all come out. A 10 mile drive should break it up, but a camping trip of 25+ miles is typically more fun.

    Fred.