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Improved and Always Improving: Reference Formulations for Thermophysical Properties of Water



Allan H. Harvey, Jan Hruby, Karsten Meier


This article reviews the state of knowledge of the thermophysical properties of water in all its phases and the reference formulations that provide standardized, recommended values for these properties for use in science and industry. The main focus of the review is the standard formulations adopted by the International Association for the Properties of Water and Steam (IAPWS), but some properties are covered for which IAPWS has not yet adopted recommendations. It is emphasized that, despite many advances over the last 100 years, there is room for further improvement, and current weaknesses and opportunities for advancing knowledge are discussed. Particular attention is given to the formulation for thermodynamic properties of fluid water known as IAPWS-95, which is planned to be replaced in the coming years. Additional topics include properties of heavy water and seawater, and the growing ability of molecular modeling to provide properties at conditions where experimental measurements are difficult or inaccurate.
J. Phys. & Chem. Ref. Data (JPCRD) -


D2O, H2O, heavy water, IAPWS, ice, molecular modeling, steam, thermodynamic properties, transport properties, water


Harvey, A. , Hruby, J. and Meier, K. (2023), Improved and Always Improving: Reference Formulations for Thermophysical Properties of Water, J. Phys. & Chem. Ref. Data (JPCRD), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed April 22, 2024)
Created February 16, 2023