What does two-billion-year-old water taste like? Scientists discovered and tasted ancient water that holds Earth’s secrets

Back in 2016, researchers in Canada stumbled upon something unusual. Nearly three kilometres beneath the Earth’s surface, they uncovered water sealed away for more than two billion years. The discovery, made inside a mine, became the oldest known water on Earth.

Geologists led by Professor Barbara Sherwood Lollar were stunned by the find. Unlike tiny pockets of trapped liquid, this water was flowing freely. “It was bubbling right up at you, at litres per minute,” Sherwood Lollar said, describing its surprising volume.

What Did the Water Reveal About Life?
Tests showed a chemical fingerprint left behind by microbes. Researchers detected sulphate, which they believe was produced by organisms over immense timescales. “The microbes couldn’t have done this overnight,” Sherwood Lollar explained. Without sunlight, the lifeforms are thought to have survived using energy from radiation.

Assistant professor Long Li added that the sulphate was not modern. Instead, it was generated by reactions between water and surrounding rock. Such processes can last as long as the two remain in contact, possibly for billions of years.