Strong support for a "mixture" model of liquid water can be found from an analysis of the accurate experimental density data (H2O) over the range t similar to -30 degrees C in the supercooled regime to t similar to +70 degrees C. Published density data can be fit to this mixture model with six- to seven-decimal-point precision. Remarkably, the output parameters from these fits indicate the presence of capacious intermolecular bonding with a density extremely close to that of ordinary ice-Ih, intermixed with compactly bonded regions having a density near that of the common dense forms of ice, in particular ice-II. Densities at higher temperatures could also be fit to good precision with such a model, though the model must clearly become less valid as the temperature rises and more varied bonding forms contribute. The fitting procedure also shows that both the capacious and dense components have positive thermal expansion coefficients that are similar in magnitude to those of their respective ice forms. As T approaches the vicinity of 225 K in the deep supercooled regime, the structure of the liquid approaches disordered ice-I-type bonding, with no contribution from the densely bonded component. Combined with the differential X-ray scattering data of Bosio, Chen, and Teixeira on liquid water, and structural data on the ice polymorphs from Kamb’s work, it can be concluded that the bonding differences between the dense and capacious structures are not at the nearest-neighbor level but occur instead in the outlying non-hydrogen-bonded next-nearest-neighbor O...O structure. Because of the long-range structural implications of this conclusion, uncertainties arise in molecular dynamics modeling of the liquid and on the usefulness of attempts to learn about the liquid from the study of small gas-phase clusters.