Comment by bluGill

I used to work in a factory that did chrome plating (I didn't work in that area, but since it was the same building), as part of my mandatory training before I was allowed to step foot in the building I had to learn there was a sewage plant just for the output of that line and if I had to dispose of waste water for any reasons I had to make sure I got it into the right system. Our sewage system couldn't treat toilet water, the city system can't treat chrome waste. (my waste disposal was limited to toilet and washing my hands - as you would expect from an engineer, but I still had to know about the system just in case)