Can someone describe for me how my plumbing is routed?

[scottandanna]

I have acquired a 5er with a less than perfectly maintained drainage system, and while I am filling both the gray and black with daily use, attempting to get them both cleaned out, I am encountering some weird issues, so I need to figure out how everything is routed under there.

So, with both valves closed, I have determined that the washer/dryer tube and the kitchen sink both bypass the gray tanks, and go straight out the sewer tube. No real big deal.

But, with both valves closed, when I turn on my black tank flush hose, I get clear "clean" water coming out of the sewer hose. Of course the water turns nasty as soon as I pull the black tank valve. If I let it run for a while, it appears to work as intended, slowly coming cleaner and cleaner over ten minutes or so.

But the water coming out BEFORE I pull the valves, is part of that flush system going to the tube after the tanks, and does anyone know if the flush is working inside the gray tanks as well?

Sometimes, when I pull the gray valve, I get very little water out of it, even if I have taken several showers and used lots of dishwater. Is this because it is filling one tank and not the second? But even if so, shouldn't they both drain when I pull the valve?

As you can see, I have to figure out how this is all plumbed so I can get the best use out of the trailer, and keep the tanks as clean as I can.