Black Tank Ideas

[Todd Klassy]

I installed a composting toilet in my new travel trailer and I am not currently using the black tank at all. I asked my dealer and a mechanic about the possibility of putting a knife valve on the black/gray tank drainage spout with the hopes that I could move gray water (using gravity) to the black tank if my gray tank is ever full and they both told me it wouldn't work, which surprised me.

If in fact that does not work, does anyone have any ideas for using the black tank? And before someone suggests filling it with beer, I already thought about that. I'd rather not have the tapper in the bathroom, though.

[norty1]

I don't see why a Thetford twist on valve would not solve that problem.

[BigJohnD]

Not sure why they'd tell you it wouldn't work. Nothing is impossible with a little thought. norty1 has the easy solution. Install that, close valve, equalize tanks. Dealers don't like to suggest anything out of the ordinary. They don't think outside the box.

[hoppers4]

On my last rig I installed a third valve on the output of the tanks. My tanks were already plumbed to a common drain and I just added a third valve (twist on valve with a clear tail piece, fits just like the sewer hose). This setup allowed me to backflush my black tank with a full grey tank. There would have been absolutely no reason I couldn't use the black tank as a grey tank. Simply open the grey and black tank valves and close the third valve (which is what I did when back flushing anyway). I can't do that on my new rig because the black tank is way above the grey tank. Arrrgggghhh. Can't use it for backflush so have to use the rinser. In your case, it wouldn't matter where the tanks were in relation to each other. If they have a common point, put a third valve on that common point and close that valve. Both tanks would drain when you open the third valve.

[Todd Klassy]

Thanks for your input. I too thought it would work, but I had two people at the same place in separate conversations and they both swore it wouldn't work. But I was almost sure my plan would work and didn't see any logical reason why it wouldn't. Thank you so much for your input. It is much appreciated.

[Todd Klassy]

Originally Posted by norty1

I don't see why a Thetford twist on valve would not solve that problem.

When you say Thetford, don't you mean Valterra? Specifically the Valterra T58 Twist-On Waste Valve? If not, what product do you mean?

[LkptRvPilot]

Is your Black tank sitting much higher than your gray tank? That would be the only issue I see to it not working.

[LkptRvPilot]

Thinking about it more, you would have two tanks worth of water pressure sitting on the piping that was probably not designed to see that static weight. The pipes are free hanging and not supported.

I'm fairly convinced that this would be OK, but I would not want to drive with all the weight sitting on those pipes, so I would at least close the tank valves if you were to move with full tanks.

[Seann45]

You can use one of these
Twist-on Valve - Valterra T58 - Sewer Fittings & Adapters - Camping World
or one of these
Flush King - Valterra FK-01 - Sewer Flushing - Camping World

[Hitch Pin]

I backflush my black tank with my grey water tank all the time.

[norty1]

Originally Posted by Todd Klassy

When you say Thetford, don't you mean Valterra? Specifically the Valterra T58 Twist-On Waste Valve? If not, what product do you mean?

Yes, is Valterra. Here is what I use. Several others make a similar product. [AT]

[fastercat]

How do you do that.

Originally Posted by Hitch Pin

I backflush my black tank with my grey water tank all the time.

[norty1]

I do it also. Just screw on the Valterra valve mentioned here, dump your black tank, then close the outer valve. Pull the grey water tank and it will backfill and equalize in the black tank. Then open the outer valve to empty the black again.

[fastercat]

is the black tank flush that is factory installed, a tornado, or some other brand, I just watched a youtube video, and the built in flush did the best job.

[Hitch Pin]

Originally Posted by fastercat

How do you do that.

I put a blade valve made by Valterra on the drain outlet, I drain the black tank first, then I close the blade valve on the drain outlet, then with the black tank valve open, I open the grey water tank valve and let it run into the black tank, then after that I close the gray tank valve and open the blade valve on the drain outlet to drain the black tank. I do this two times each time I dump, works real good.

[Todd Klassy]

Thanks again for everyone's input.