Hydrogen and deuterium isotopic evidence indicates that the source of terrestrial water was mostly meteorites, with additional influx from nebula gas during accretion. There are two Earth models, with large (7–12 ocean masses) and small (1–4 ocean masses) water budgets that can explain the geochemical, cosmochemical, and geological observations. Geophysical and mineral physics data indicate that the upper and lower mantles are generally dry, whereas the mantle transition zone is wetter, with heterogeneous water distribution. Subducting slabs are a source of water influx, and there are three major sites of deep dehydration: the base of the upper mantle, and the top and bottom of the lower mantle in addition to slabs in the shallow upper mantle. Hydrated regions surround these dehydration sites. The core may be a hidden reservoir of hydrogen under the large water budget model.

氢和氘同位素证据表明，陆地水的来源主要是陨石，在吸积过程中还有来自星云气体的额外流入。有两个地球模型，大（7-12 个海洋质量）和小（1-4 个海洋质量）水预算可以解释地球化学、宇宙化学和地质观测。地球物理和矿物物理资料表明，上、下地幔普遍干燥，地幔过渡带湿润，水分分布不均。俯冲板片是水涌入的源头，除浅层上地幔中的板片外，还有三个主要的深度脱水位点：上地幔底部、下地幔顶部和底部。水合区围绕这些脱水位点。