Plating operations are a huge headache. They have corrosive plating baths. They have to do some chemical processing on site to neutralize the corrosive chemicals and get them down to a neutral pH.

Some years ago, a plating company in San Jose dumped a plating bath into the sewer system. This was so toxic that it killed the bacteria that reduce organic sludge at the sewerage plant. This knocked the whole plant offline, releasing untreated sewerage into the bay. The lower bay was toxic for a week. It's normally swimmable. San Jose was fined by the EPA. The plating company was heavily fined by San Jose.

It's a good sewerage plant. The output is drinkable, and if you take the tour, you're offered some to drink. Some of the output is used for irrigation. In a severe drought emergency, water could be fed back into the water system. They've never had to do that, but in a big drought a few years ago, things got close to that point.

San Jose, which is more of an industrial city than most people realize, still has plating companies. Here's an inspection report for one of them.[1] This one was releasing too much chromium.

[1] https://19january2017snapshot.epa.gov/www3/region9/water/pre...