(Three were installed after the fact and may be kosher, and I've never even bothered to count the wires in the one of my original eight. In fact, the super doesn't even bother with an adaptor when he installs a new refrigerator...merely clips the grounding prong.)
Okay your stereo probably isn't properly grounded to a "metal stake driven into moist earth". 😖
People in my neighborhood seem to have abandoned tap water in favor of Poland Spring, but that deprives their kids of the fluorine.
Personally, I'd risk the contaminants, which don't appear to be anywhere near critical, rather than confer lifelong dental problems on my kids.
I remember several years ago
Consumer Reports ran a series if articles on water. They used New York City tap water as the
gold standard for taste, odor, and purity against which they compared water from cities all over the continent and major brands of bottled "spring" water, filtered water, and distilled water. Their conclusion was everyone should drive New Your City water. What has happened in the interim?