Connecting black and grey tank

[Mainely Fish]

I have two 42 Gal tanks in my pick up bed under a Leer cap. They are stacked. Top is fresh water and will gravity feed into our 22Sport. When needed I pump the gray from “shiny” into the bottom tank. It drains by gravity at a dump station. We travel with the thanks empty as often as possible but with only a 20 gal fresh and only the same for grey they both allow for dry camping or easy dump and fill at lots of dry site in State parks.

[Mario Simard]

Originally Posted by Rocinante

Yup, I wouldn’t combine the two tanks this way unless I had a composting toilet (no black water anymore) and had thoroughly cleaned out the black tank before never using it for black water again. [emoji6]

This is what we have done (Naturehead composting toilet and two tanks connected with valve as described above). Works great. Only limitation : on our 22FB, the black water tank is partially higher than the grey water one so we cannot fill it completely because the grey water tank would overflow in the shower. We did it before ever using the regular toilet. No contamination issue, our black water tank was still a virgin...

[Msherw]

Originally Posted by Mario Simard

This is what we have done (Naturehead composting toilet and two tanks connected with valve as described above). Works great. Only limitation : on our 22FB, the black water tank is partially higher than the grey water one so we cannot fill it completely because the grey water tank would overflow in the shower. We did it before ever using the regular toilet. No contamination issue, our black water tank was still a virgin...

I think I will look into a composing toilet if my blackwater toilet fails. I'm choking (pun) on the prices and think I will leave everything as is for now.

Wife and I boon docked for 4 days with no sewer outlet. Having city water input made it difficult to manage sewer. If you have unlimited water input but very limited black/grey holding, unless you can mentally manage it, it will bite you. Too easy to turn on and forget there is no easy outlet.

So in future boon docking, I will only fill the internal tank and use it on pump. That will keep us honest on showers etc.

[Boxite]

Originally Posted by BigAl

There is one instance when the back flow preventer will do it's intended job. If the black tank water level is higher than the nozzle on the tank rinser and the supply hose is connected to it but not hooked up the city supply then water cannot siphon out of the tank. The reason for the code requirement is in the off chance that while you are rinsing the tank out the supply water is shut off at the main. Then waste water could siphon back into the supply system. When turned back on the main supply would be contaminated.
Same as why a bidet must have a back flow preventer.
Al

I see your point, Al... but for that to occur...one would have to connect the hose to a full black tank and leave the hose connected without ever applying water pressure to it. Why would anyone connect a water hose to a full black tank...if the purpose of the excersize is to rinse out an emptied black tank?
And who is the brave person to apply the suction to that hose which would be required to start a siphon?

The purpose of the backflush is to rinse out an EMPTY black tank, in which case the scenario described cannot occur. But thanks for pointing it out.

In my case, my backflush system did not work at all. When I found that cheap little plastic backflow preventer was clogged with a "cigar" of leaves wrapped by some insect... and coupled with the prospect of a cheap plastic fitting breaking or freezing... I tossed it...and replaced it by cutting the PEX cleanly and installing a "sharkbite" elbow. No more backflush problems whatsoever. (But I only backflush after my black tank has already drained.)

[xrvr]

So much of this is common sense and paying attention. A trailer is not like a house!

[jmm0119]

Originally Posted by Mario Simard

This is what we have done (Naturehead composting toilet and two tanks connected with valve as described above). Works great. Only limitation : on our 22FB, the black water tank is partially higher than the grey water one so we cannot fill it completely because the grey water tank would overflow in the shower. We did it before ever using the regular toilet. No contamination issue, our black water tank was still a virgin...

Just purchased a 2018 International Serenity 25RB along with a natures head composting toilet that I plan on installing before the toilet ever gets used. Can u send me some pictures of how you vented the natures head. I was thinking of tying into the black tank vent. Any suggestions would be greatly appreciated.

[Adventure.AS]

Originally Posted by jmm0119

Just purchased a 2018 International Serenity 25RB along with a natures head composting toilet that I plan on installing before the toilet ever gets used. Can u send me some pictures of how you vented the natures head. I was thinking of tying into the black tank vent. Any suggestions would be greatly appreciated.

You will find that the vent runs behind an easily accessible panel in the corner of the lavatory.

[Mattirs]

There is an emergency way of moving grey water to black water tank, but it only works if there is a good head difference between the gray and black water tanks. You leave the cap on, open the gray until the waste piping is full. Leaving the gray valve open you open the black water tank valve. The gray then runs into the black tank to equalize the water levels. While the gray water is still flowing into the black tank, close the black tank valve. This keeps the black from mixing back into the lines. This works if you have a good head and don't wait too long.
The problem with this is you will spill gray water when you go to dump.

[Msherw]

Originally Posted by xrvr

So much of this is common sense and paying attention. A trailer is not like a house!

Yes it is XRVR. Thinking person's game.

What we all must do is know our TT, understand the plumbing inputs/outputs, become familiar with our camping environment prior to hookup, manage the use of water and electricity as dictated by the limits of our site, and carry enough 'extras' to fix unforeseen issues.

Personally, boon docking is the best way to really get a handle on the basic elements of our AS.