Finished fab on the passenger side and moved over to the driver side only to find that as far as I can tell there is no gray tank and just a 1 1/2" black drain that runs from the kitchen sink on to passenger side to the rear of the driver side and then it just joins the black tank drain right at the exit. The shower and bathroom sink just go to a p-trap and then T into the pipe a foot before the main drain. Question, is this normal? Can I just open the 2 shutoffs so the gray water can go in the black tank, but that means there will be some crappy water to deal with in order to open the drain, so probably not?????