Dick_B wrote:
IMHO that's asking for trouble.
First of all, a garbage disposal would have to go into the black tank, not the gray tank.
It should be noted that the amount of water you use to flush the disposal unit would fill up your black tank pretty quickly. Heck, it'd fill up the gray tank quickly, too.
Gray water is supposed to be minimally polluted, containing just soapy water from washing things. Black water is where the heavy biological stuff goes.
They are separated on an RV originally because it was legal to dump the gray on the ground many places. This is no longer true, BUT, they are still separate so you can use the gray to help flush the stinky slinky of its nasties. If the disposal went to the gray tank, this would no longer work, and you'd be having to do some major rinsing out every time you dumped.