I think people need to become a little more...umm, realistic about "fragile eco systems."
First of all, opening your gray tanks drain is very different than taking a sun shower.
Every time you press that windshield wash button using that lovely blue fluid, you do a LOT more to damage our planet than a sun shower.
Same with a rig overheating and blowing its coolant-cookies all over the road. Anti-freeze, unlike water with ecologically friendly soap, lives on in the gifts of toxic deposits for years to come.
When Mrs G and I were next to the Salton Sea, we had a shower tent with a solar shower. A tree hugging do-gooder walked over and began ranting about the "fragile eco-system" we were defiling. Salton Sea, folks. Salton Sea. I roared with laughter and began my own shower...as I reminded them to consider the location and praised them on the wonderful job they had done "Armor-all-ing" the tires on their off-gas-wonder of a brand new mid-life-crisis machine...evidenced by the huge wet spots for each of the tires, still on the ground from the previous day.
Lets use Quartzsite as an example.
If you use Ivory soap or decent camp castile soap, the tiny amount of impurities left behind on the ground are less than a few drops of sweat that is loaded with sun screen.
In a desert situation, the "run-off" does not last ten minutes. POOF! It is gone into the air.
The green-minded hikers who dig a 8 inch hole for their poop in the wild do a hell of a lot worse for mother earth than a showers water on the desert floor.
Same with pooping in a bag and tossing it in the garbage. An adult sized turd, mixed with three thousand other adult sized, plastic wrapped turds...makes an environmental disease-spreading nightmare.
Prattle on about how people dump baby diapers in the trash...just because they do not empty the waste like the diaper packages used to instruct...does not make it right.
Un-treated human feces in a landfill is toxic stuff when you wrap it in a plastic protective skin that does not allow it to dry out and go through the decay process.
What about washing a dog?
What about "out door showers" being installed on many RV's?
The "let no water hit the ground" attitude becomes much more laughable @ the BLM lots in Quartzsite.
The few times it rains there, the run-off from the millions of gallons of wax, spray tire cleaner/protectants, Rain-X, "sealant cure" run-off from the recent roof job, oil dribbles from the leaky skoolie diesels (Detroits...SHIVER) it all adds up and some of the preceding examples are far more harmful than a little DAWN and macaroni chunks.
The "WD-40" you spray on that squeaky door hinge has a ton of over spray. It does not evaporate.
I bet you could take a hundred sun-showers and still not equal the environmental impact of one good "spray job" from some of the RV people I have seen, who like to liberally wash their rigs down with the stuff.
We do have to draw the line somewhere. There are things we could be doing better. Showering on the ground isn't one of them.
When you put poop in the garbage, you are dumping waste that...in other settings, has to be labeled "BIO HAZARD" and disposed as such.
Rationalize it however you like...the fact remains, wrapping/tossing poop and finger-wagging at ground-release bathers is an example of grotesque hypocrisy.
