I was doing some mods on the under-bunk storage area today putting in support to hold the lid up:

Then I decided to look under the other part that is screwed down to see what is under the area of mystery. (I'm just nosy!)
Here's what I found:

On the left is the shower/toilet wall, and the right side wall is the garage area of our 182G. The white hose is the sewer flush-out valve that wraps around and disappears into the shower wall. It had been zip-tied to the cold & hot water lines, and had a major kink in it - I'm surprised any water got through at all. You can see the kink after I removed the zip tie.
I was surprised to find out that the flush-out hose does not go directly into the black tank, but instead goes up the wall where the small sink is in the wet bath:

You can see it return back down on the left side of the hot/cold lines, then go into the black tank. I couldn't see where it went, but I suspect that the relief valve that another poster was having problems with (sprayed water on her floor when black tank valve was not opened) is mounted up behind the sink. By the way, the black waste line is from the sink in the back of the garage area, and goes directly into the GRAY tank, not the black tank like others here have mentioned about their 181G's.
To fix the kink, I moved the white hose over and clamped it and screwed it down in a position where it would not kink again:

If I have time in the future, I may see about putting hinges on this lid, building a box to set in here so as not to have loose cargo hitting the wires/lines and take advantage of some of this wasted space.
My question is: would this kink in the hose to flush the black tank be the reason why the relief valve ended up spraying water on the floor of the other poster's Pod? Or was is just because the black tank valve was not opened up? If FR kinks this hose on all the models that have a sewer flush line, it might be a possible explanation...you never know. Some of you might want to look into this area and see what's there.