QG, you are right, but then as few as we analog photographers are, we contribute very little to the impact on the environment. Even a photofinisher contributes little in terms of water usage when you get right down to it.
Many industries use far more water than the entire analog manufacturing and processing chain are concerned, or they introduce far worse pollutants. Photography is quite mature and the engineers working in the field have considered the questions I bring up. In fact, I think that consideration of some of these facts and questions have given rise to the ambiguity and sometimes to the apparent retractions in textbooks.
The bottom line is to use what gives you the right level of retained hypo and silver at the lowest level of pollution.
And remember, when you dump exhausted developer and/or fixer, this is hundreds of times worse than the wash water contamination.