Even though commercially prepared flavored waters abound, I never buy them, since they always taste artificial. The lemon doesn’t taste like real lemon, nor does the lime. Just because a label says “natural flavors” doesn’t mean it wasn’t produced in a laboratory. And even so-called spa water, the sort that you see at saunas and in hotel lobbies, can be too complicated. For sweltering summer days, I prefer to infuse a pitcher of cold water with just a few aromatics.