Re: soo...
"there was also additional challenges from businesses and people pouring random chemicals down drains"
We had a problem with the Belfast sink* (in Belfast) leaking. I had a few goes at tightening up the fixings with no success. Eventually the penny dropped. It was the sink we used to dispose of reagents used to prepare samples for pollen analysis. For soil samples this involved boiling with hydrofluoric acid.** It was an old building so the sewer pipes would also have been glazed; I wonder what it did to them.
* For those who don't know, glazed earthenware.
** Sporopollenin is amazingly resistant to all sorts of things.