Yep, the no
grey water is a scale thing and LCID thing (lowest common idiot denominator). The problem isn't that people are going to get sick because you dumped your dirty cooler
water on the playa or that by dumping dirty cooler or shower
water you're somehow going to upset the delicate ecosystem of the playa chicken, rather the problem is that most
water will have some kind of floaties in it be it food particles, packaging labels, body paint, hair and other tiny moop particles.
My solution for
grey water this year is to filter the particles out using an aquarium filter pump and then to purify the
water using the Miox
filtering system (designed for backpackers, it's the same system the U.S. Navy uses aboard it's ships). It's small, relatively inexpensive, purifies gallons of
water at a time and will mean using much, much less
water for showers, and therefore much less
grey water to deal with (I plan on packing all the
grey water home).
Check it out:
http://www.msrcorp.com/filters/miox.asp