Quote Originally Posted by Gerald C Koch View Post
Kodak in one of its publications states that there is no adverse effect on septic systems from the amateur darkroom. The professional darkroom is another matter.
Gerald:

I'm afraid Kodak's publications no longer make this statement.

Darkroom Design for Amateur Photographers • AK-3 explicitly states the opposite: http://www.kodak.com/global/en/profe...bs/ak3/ak3.pdf

Environmental Guidelines for Amateur Photographers • J-300 is the best Kodak reference I can find on the subject: http://www.kodak.de/ek/uploadedFiles...er/J300ENG.pdf

That being said, I don't think the trace amounts the OP was asking about (in the rinse and wash solutions) are of concern.