Ugh... pseudoscience at its best.
You don't want to KNOW how much Saccharomyces cerevisiae you've been ingesting. Or Lactobacillus acidophilus and casei. It's just gross!!
Look, there are living things everywhere. S. cerevisiae makes beer and bread. L. acidophilus is youghurt. L. casei is cheese. Even E. coli isn't the villian most people think. Most strains of E. coli are beneficial and are already living in you right now. They're making vitamin K, and preventing other infections, just by being bigger and meaner.
There was a time, way before public water systems, when drinking beer WAS the only safe way to go. Boiling the wort killed a lot of bad things, then the yeast would scare off any new bad things.
In the modern world, you're in more danger from your own lead pipes than the from the water inside them.
Dad worked in a water works...so I'm a little sensitive about this. 'Course that was at 10,000ft above sea level. The advantage of living in the mountains is that nobody's had a chance to poop in your water, yet.I also brew my own beer!