Tyler,
Your post begins with a fallacious assumption that "grey water" is pollution. In fact, "grey water" is environmentally harmless -- which is why it's still legal to discharge it. The "grey" in the water comes from dirt, perhaps occasional food particles if it's from the galley, and a little soap. The dirt is naturally present in the environment, and therefore obviously is not going to cause any harm. The food particles and soap are biodegradable organic material, and algae in the ocean actually feed off of this stuff -- thus ensuring that it does not last very long.
Neither I nor any other responsible person will defend practices that are harmful to either the environment or any local ecosystem. On the other side of the coin, though, there are too many environmental zealots who charge ahead madly on the assumption that everything is harmful and must be stopped without bothering to do their homework and learn what really is harmful. Altogether too often, honest scientific investigation shows that their efforts are seriously misguided.
Norm.