So I've done some searching and find material relating to situations rather different from mine. Mine is an extremely sensitive case that perhaps deserves its own thread. Hopefully you chemistry types can help me. I'm considering putting my darkroom back together in a new (to us) home. However, I'm mindful that we have a septic system on a hillside that leaches down into a tidal pool that is an estuary where a large population of fiddler crabs hangs out. These crabs are eaten by all variety of water fowl. So I'm concerned that whatever I put down a drain goes fairly directly into the local wildlife. My question should be obvious. As there is no waste treatment plant to take care of my tiny bit of pollution, so I have to do this myself. I am mostly interested in developing B&W film. Although I might do some printing, I suspect my workflow would be mostly digital, beyond the film. I'm uninterested in using toning agents. I need to determine the following: What is safe to go down the drain as it is? I'm thinking stop bath is fine -- acetic acid. How can I modify/treat any chemicals that are unsafe in their exhausted form? For instance, I know I can reclaim silver electrochemically. What chemicals cannot be modified/treated adequately and must be disposed of elsewhere? Thanks for your help!