I apologize for not humbly submitting to the first comment on HN. If I gave the impression that you were not the ultimate authority on this topic, I certainly did not intend to do so. I should know better than to oppose common sense on a topic that is way over my head.
I'm definitely not the ultimate authority on this subject or any other but you are either interested and want to know about this or you can keep putting up objections that are masked as questions which seems to be what you are doing.
The main reason we are talking about this is because 'environmentalists' (which in itself gives a hint about the levels of expertise) are worried, they are not worried for no reason. Listing a multitude of reasons should at least make you pause about whether or not they are sincere in their concern.
The degree to which industry would wreck the environment if we let it is by now very well documented. But the EPA has been gutted and lots of safeguards have been abandoned in the name of 'progress'. This is not without risk and I am very happy that in spite of all this a lot of people are still willing to speak up and to make sure that at least the worst excesses are curbed.
You can approach this with curiosity to try to learn about the subject and to try to understand what drives the worry of people that have studied this stuff for a long time. These are not just idle musings. Or you can put up a barrage of questions effectively casting doubt on anything that might be of concern.
The problem with environmentalists is that it is full of militants that aren't engineers and have very strong opinions that don't pass the most cursory smell test.
I am all open to there being problems with re-using water used to cool datacenters (hence my question). But 1) "it boils" defies common sense, no component in a computer should run at >100 degree celcius continuously, so I find it hard to believe that datacentres boil water (and I would have noticed the big cooling tower on the side of them). 2) Legionnaire disease is certainly a big deal in residential buildings with stagnant warm water, sitting in pipes sometimes for days until someone takes a shower. I fail to see how it is a major issue for a continuously flowing industrial application where the water spends very little time at elevated temperature and is continuously flowing before being released into colder water. 3) "contact with metal is bad" certainly doesn't come from someone who has seen the water supply chain in the UK or any European country with ancient infrastructures. Many of which are still made of lead. 4) "water is then not suitable for human consumption", well neither is the water in a lake. All drinking water has been filtered and sterilised. I would be surprised water used for cooling has been treated that way. So unclear to me why there would be any expectation that the water coming out of a datacenter should be any cleaner than the water coming out of a lake.
Now there is common sense, and there are regulations. The two often form a perfectly disjoint venn diagram. So I am happy to believe that there are regulations resulting in absurd situations. But from an actual risk point of view, I don't see how a datacenter "consumes" water, in any comparable way than a swimming pool, agriculture, chemical plants, or gardening, where the water cannot be used for anything else after that. To me it is more akin to a nuclear power plant, which releases water at a slightly higher temperature (despite actually boiling it), and therefore has a fairly limited impact on the water supply.
