I can tell the difference between my cities perfectly adequate and safe tap water, and water that's from a Brita.

There's literally nothing wrong with my tap water at all. I use a Brita because I don't like the taste of my tap water.

I know exactly zero other people who can tell the difference.

You can typically look up your city's water test results and see what's in there or do your own testing. The vast majority of municipal water is plenty safe, and most issues with stuff like elevated lead come from the home/building itself, not the municipality.

Oh I have RO, one of the first things I put in when I bought the house, and already had to replace it once, the last one took really obscure filters that were hard to find, it ended up being simpler to replace the thing with one that took more common replacement filters. And I've tried more ordinary filters, it makes it better, but it still tastes funky, I prefer RO.