Drink it, of course.
A researcher who analyzed water found in a Canadian mine in Timmins, Ontario, did just that. The water is between 1.5 and 2.6 billion years old, meaning it has been totally isolated for that long.
Dr. Barbara Sherwood Lollar, geologist at the University of Toronto, dipped the tip of her finger in this water and tested it with her tongue. She found the ancient sample "very salty and bitter -- much saltier than seawater." No worries there.
You can pretty much ignore CNN's otherwise cliché-ridden piece beyond that, everything after "This research has implications for what life may exist on other planets."