I've always wondered why the gray water drain is half the size of the black water.
I understand that the black tank needs to have a larger drain to handle the "fulsome effluence," but the dump station lines would move a lot faster if the gray water drain was a large line too. I had a small Winnebago MH that had large drains on both tanks. At the dump station it was Woosh! Woosh! Done.
My theory is that it might be another example of MBA mischief - save a few cents on smaller pipe and boost profits. I'd like to believe that there's a better reason. Hopefully someone has one.