Something like 15 years ago, a large manufacturer had a Legionella outbreak involving both assembly line workers and the front office administration staff. I first designed the technical means to disinfect the facility water system (about 6000 GPM), obtained corporate approval then implemented onsite 2-days after approval. This was costing the company about $1MM per day in revenue. About a dozen persons contracted Legionella but thankfully no fatalities.
All told, the facility was shutdown about 10-days. About 3-days of that was simply due to a single jerk union steward that wanted his pipe fitters to turn water valves on and off for us. My field team had to stand down until the steward cycled off duty.
After the facility was up and running, I put together a different team of engineers and we traced every single waterline in the entire facility. We found the piping drawings to be out of date/inaccurate. It turned out that non-engineering approved modifications to the water distribution system over the years had left a number of deadlegs in the potable water system and 2 of these had led to Legionella contamination and human exposure.
Interesting.