Originally Posted by dmoore
I can't understand why this is such a problem. In our home bathrooms (and all others) doesn't the sink/shower water drain into the same place that the toilet does?
Yes, but not into a holding tank. A permanent structure is hooked to a public sewer system or a septic tank. All waste drains into the same place, but it goes away, usually never to be heard from again.
In an RV, normally the toilet drains into the "black" tank, and the sinks and shower drain into a "gray" tank. In the old days, gray water was allowed to simply drain onto the ground, and RVs didn't have gray tanks.
Knowing what drains where is important, so one does not overfill a holding tank and have used water showing up in the living space floor or shower.
If you think all the sinks are going to the gray tank and have it hooked to a dump site with the valve open, you can assume all the water you are using is running out as fast as you run it in. But, if said sink is filling the black tank and not leaving the trailer, in a little while you will have a stinky problem running over the top of the toilet.