"The Life Giver", with many variations, is a nickname passed down for the element H2O from ancient monoplanetary civilizations. Water is used by Empyrion survivors to meet various basic needs.
Water provides oxygen. Survivors use Oxygen Generators placed in water to create Oxygen Bottles to put in their Oxygen Tanks to fuel the usage of their Oxygen Stations. The Station is equipped to recompress a space suit once emergency supplies of Small Oxygen Bottles run out.
If a survivor has Experience on a planet, they may eventually use a late-Tech Tree device called an H2/O2 Generator to create Oxygen Bottles, but also Hydrogen Cannisters which become Fuel Pack (Hydrogen).