I'm crazy for this stuff.
I of course picked up the sparkling mineral water habit in, where else, Italy. The Italians take their water very seriously indeed. No doubt this has roots going back to ancient times, as the Romans obviously went to great lengths to transport water into their urban centers, building elaborate and very sophisticated aqueducts to transport the stuff from way up in the mountains. (Of course, these same aqueducts were ultimately the downfall of ancient Rome, but that's another matter altogether.) Water to them is more than a mere beverage; it's a birthright.
I loved seeing the Italians go to their local spring source with empty bottles, filling up and taking it home. Depending on your tastes -- sparkling or no, more or less mineral flavored -- there are different springs to go to. In America we seldom go further than the tap or the fridge. In Italy it's not uncommon to go for many miles out of town if you have a particular liking. Of course, many people also simply buy it bottled at the local store, avoiding the rigamarole.
Curiously, my cousins buy sparkling water, yet they leave it uncapped in the fridge, where it goes flat. I never asked why, but I surmise they must like the more mineral flavor of the sparkling water, but not really care for the actual bubbles so much.
I, on the other hand, have always had a strong penchant for bubbly things. I like my water sparkling, with delicate, steady effervescent, and with a pronounced mineral flavor. And Gerolsteiner fits the bill perfectly. Of course, I also like Pellegrino, Acqua Panna and other Italian varieties, but this stuff really works for me on all levels. Best of all, I can buy it by the case for chump change at Trader Joe's.