If the question of environmental damage comes up, let them know that most of the chemicals used in wet photography are organic, naturally occurring (stop bath is basically concentrated vinegar, even COFFEE can be used as a photo developer!), and those that are not can be handled and processed safely (silver recovery from spent fixer). And unless you are on a septic system and/or get your water from a well, the average home user poses zero risk to a modern public sewage system. All their neighbors on Prozac and Xanax are causing infinitely more pollution than the odd batch of film and prints.