Billion year old drinking water,.... found in a Canadian cave,.... if you like very salty water....

isolated in the rock for roughly two billion years. That is older than animals, older than plants, and older than almost everything most people picture when they think of life. When that water was last in contact with the surface, the only life on Earth was microbial. The researcher who led the work, Barbara Sherwood Lollar of the University of Toronto, tasted it.

More at link below,...

https://spacedaily.com/t-nearly-three-kilometres-beneath-a-canadian-mine-geologists-found-water-that-may-have-been-isolated-in-the-rock-for-roughly-two-billion-years-older-than-animals-plants-and-almost-everything/