Wow ... the greenie movement has really warped some attitudes...
What do you think the tenters do with their grey water? Somehow putting it in an RV grey water tank has elevated dish washing water to SuperFund toxic levels?
I don't suggest that 200 RVers in a developed campground all dump their grey water on the grass and bushes but ... really, folks? It's just soapy water ... and not all that much soap, probably.
You know what the horticulturists (and Old Farmer's Almanac - oops, there's the "old" think/thing again ...) advocate for lawns? A little dish soap ...