Right, they're so power efficient they don't want to tell the people around them how little water they consume or "not consume"?

People complain about new data center slurping up all local water and then neither Google nor representatives can say "No, actually we're not, here is the numbers", because Google doesn't want their competitors to guess how many machines they have in one of their data center? I'm sorry but that sounds very far-fetched, must be another reason parent wrote it was "obvious" they couldn't divulge how little/much water the place uses.

Tbh this sounds perfectly normal to me. Companies often don't think it's worth defending themselves if theres no actual financial damage, and certainly don't want random employees to be doing it. It can be very frustrating, both for employees who want to defend their reputation and for the public who want the truth, but companies can be extremely conservative about chosing their public relations battles.