I honestly don't know. Twenty years ago, when I last did wet darkroom, I just poured things down the drain. Maybe lots of two-headed babies in that neighborhood? In the conventional B&W process, the silver gets dissolved out in the "Fixer." Commercial labs process the fixer to recover this silver. It is a heavy metal, but do not know if it is considered an environmental contaminant. The basic "fixer" material, Sodium Thiosulfate, should not be any big issue. Some of the B&W developers are skin irritants, and the stop bath, (itself being harmless vinegar), will contain traces of the developer. Damn! Even the WASH water may be an issue... C-41 B&W processes, or color, is a different game entirely. Formaldaheyde is definitely part of the process (I forget which), and is nasty, nasty stuff in the environment. [But I think, from what you've said in the past, that conventional silver processes are more your interest? For C-41, go to Quicky-Mart. I always used Dektol for developing (fiber) prints. Maybe Selectol if I was doing some funky chloro-bromide paper, but you seem to like the cold black tones. For the "plastic" based "papers", use whatever the manufacturer recommends. Film processing is where you can still make a lot of difference. General work was always D-76. My favorite was using a very fine grained B&W film, ASA 32, and processing it with VERY SLIGHT agitation in an active developer like Rhodenol. HC-something-or-other was also a good general purpose developer. ___ This is a REALLY good thread! Is there ever ANY reason to use the conventional B&W darkroom at home? Are the C-41 processes "just as good"? Do the conventional processes destroy the environment? Is this a motivation to go Digital?