Prices range from $8 to $20 and if you can't decide, just ask for the water sommelier. Martin Riese is the certified water sommelier. (Yes, he assures me there is such a certification.) He also, literally wrote the book on water, "Die Welt des Wassers." www.amazon.com/dp/3865286666 (Hope you can read German.)
He took me on a mini global tour of his water offerings. We started with Fiji water, one from Iceland, one from France and a strange one from Spain. Riese also has his own bottled water which he formulated by taking a California spring water, then adding minerals for a water perfect for both wine and food. It's what he calls the "first sommelier crafted water in the world."
And, it has a clever name, Beverly Hills 90H2O It's $12 bucks a bottle on this site. http://beverlywater.com/ But at Ray's and Stark it's the second most expensive bottle on the water menu.
I must admit, I couldn't appreciate much difference between the Icelandic Iskelde and the Fiji, but the strange one from Spain, really made my eyes pop. It's one of two sparkling waters, he served me. Vichy Catalan is so high in minerals, the water is actually salty. Don't pair with food, Riese advised, but it would be good as an appertif; something to ready you for the meal. Still not sold?
Martin will happily serve you LA's finest tap at Ray's and Stark Bar; it's filtered and free. Here's the best thing about a water tasting? You don't have to worry about drinking and driving.