Water

Water is an extremely common liquid. It can be produced anywhere using Well or Water Generator. It also exists on Ocean planets in infinite quantities.

It's notable for being usable for watering plants, for being a part of many mixing recipes (something+Water = something else), and also as a source of Deuterium (a valuable fuel).

Water plays an important role in infinite mixing of several other liquids, including Poison, Healing Water, Sulphuric Acid and Organic Soup.