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When did liquid water first exist on Earth?

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abundance of oxygen — evolution of the atmosphere A “best guess” reconstruction of the abundance of O₂ in Earth's atmosphere as a function of time. The O₂ abundance axis is logarithmic.

Evidence suggests that liquid water existed on Earth at least 4.4 billion years ago. While direct physical evidence from that period is extremely limited due to the dynamic nature of Earth's early crust, analysis of ancient zircon grains provides compelling support for this timeline. These zircons show chemical alterations consistent with exposure to liquid water, indicating that surface temperatures were likely cool enough to support its presence shortly after the planet's formation.12

By 3.8 billion years ago, there is more definitive evidence of water in the form of water-laid sedimentary rocks. While the exact timing of the initial accumulation of surface water remains a subject of scientific study, it is generally understood that water vapor released through volcanic outgassing eventually cooled and condensed to form the early hydrosphere.3415