Your reference to orthorexia is extreme. There's nothing in the parent comment that would take my mind there. It's true that relatively few people realize how polluted drinking water has become - lead and other metals, PFAS, plastic particles - take your pick. I have a hard time understanding why any knowledgable person who can afford to do so wouldn't filter all or almost all of the water that they drink and cook with at home. OP also didn't mention distillation as a filtration method. A reverse osmosis filter with a remineralization stage is vastly more popular and a no brainer to install in any kitchen. If you do drink distilled water then you can supplement with an extra pinch or two per day of salt and minerals in your food and you will be fine.

Orthorexia and OCD tendencies are real and destructive but I'd be equally wary of normalizing the oftentimes highly toxic exposure of modern life to the point where anybody who express tangible concerns and takes meaningful countermeasures is pointed to as a potential basket case.

I appreciate the concern! I actually salinate and mineralize my own water, and agree that it's a necessity. I don't trust the pipes to keep my water clean, and I don't trust the local rocks to mineralize it properly either. I agree this take is unusual, but I don't think it's paranoid. On the contrary, I think it's realistic. Lots of pipes and rocks have documented problems.

Is it Orthorexia to worry about tap water? At least in my case, I don't think so. I'm a very unusual case in a lot of ways, but I'm very sure what I am doing helps me. Looking at broader society? I mean, I know we as a society have problems with chronic and widespread dehydration. I know relentless messaging to people to drink more water doesn't seem to help. I know in my case, the problem certainly wasn't in the motivation, but in the filtering. Maybe I'm weird, but wondering if this is more widespread doesn't seem like an unnatural guess to make, particularly when it comes to a water-heavy activity like nursing. None of this seems paranoid to me. Eccentric, sure, inconvenient, sure, unpopular, sure. But if this is all crazy, I don't see how.