Grey tank and black combination

[Nan]

Is there any way to combine the black tank with the grey tank? I have a composting toilet and could really use the extra storage the black tank could provide. 

Thank you.

[Ronbrink]

I have no first hand knowledge of this, but the question has been raised before; hopefully someone will come forward with an affirmative answer.

[mossemi]

Here is NCeagle's process to accomplish this task!
 https://olivertraveltrailers.com/forums/topic/5345-easy-way-to-repurpose-an-unused-black-tank-for-grey-water/

Mossey

[rich.dev]

@Nan yes this question has been raised by many (including myself) before. In most RVs, the grey and black water tanks are separated but come together to flow through the same opening when it comes time to dump the tanks. So something as simple as adding THIS valve will allow the black and grey water tanks to be connected and for liquid to flow between the 2 tanks. However, with the Oliver valve configuration I don't believe that would be a possible option, unlesss you add one of those valterra blade valves right at the outlet. But also, if I remember correctly the grey water tank sits slightly lower than the black tank so that could be an issue as well (water going "uphill" from grey to black). Anyway, here are some threads with good reading material and possible solution for you....

Please let us know if you come up with another solution, I would be interested as well.
 

 

[2008RN]

I use a 12volt pump, kind of cheap and manual, but I hook it to the output for dumping, and then connect to the spray port on the black tank.  I do have a fine mesh filter on the pump so no debree gets stuck in the sprayers.  I have used it when we are boondocking greater than 4 days.