High water concentrations (4–6 wt%) are found in the quenched glass inclusions of phenocrysts of explosive silicic and intermediate eruptions. Accordingly, we have measured the solubility of water in a wide range of natural liquids up to 2 kbar. With data from the literature, we have developed a simple, thermodynamically based empirical model for the solubility of water as a function of temperature (700–1200 °C), pressure (1–2000 bar), and composition. The model works well for both pure H2O and mixed fluid compositions, fits the data to ± 0.5 wt% (2σ), and may be used to successfully model the degassing and eruption behavior in most volcanic systems, as well as the magmatic exsolution processes that lead to ore deposition. Due to the nature of the regression, however, it should not be extrapolated to conditions beyond the range of the data.