IAPWS provides recommended formulations for numerous properties of water, steam, and aqueous solutions. These fall in several categories:
Releases provide carefully evaluated, internationally agreed-upon data and formulations of properties for which measurements of high quality exist over a wide range of states. They are intended to embody the state of the art for representation of the property at the time of the Release.
Supplementary Releases provide supplementary material to an existing Release, or provide specific (perhaps simpler) formulations for a subset of the material in an existing Release. They are intended to be of the same quality as Releases.
Guidelines are similar, but for properties where the quality or range of the available data is limited. They are therefore not expected to provide as definitive a representation as Releases. Guidelines are expected to require revision when new information is available.
Advisory Notes are documents that give additional information and guidance that is intended to be useful for users of IAPWS property formulations.

A different type of IAPWS document is the IAPWS Certified Research Need (ICRN), which is a statement of the need for research on a specific topic. ICRNs are listed on a separate page.

An additional type of IAPWS document is the IAPWS Technical Guidance Document, giving international consensus guidance on aspects of cycle chemistry for fossil and combined cycle power plants. Technical Guidance Documents are listed on a separate page.

All current IAPWS Releases, Supplementary Releases, Guidelines, and Advisory Notes are listed below (with the most recent at the top of each list) and are downloadable as PDF files.
While IAPWS does not produce software, many IAPWS formulations have been implemented in software produced under the authority of the National Committees of IAPWS member countries; this page has links to these sources.
A separate document is available describing obsolete IAPWS recommendations that were issued in the past but are no longer current.

Releases

• Release on the IAPWS Formulation 2011 for the Thermal Conductivity of Ordinary Water Substance (September 2011)
• Revised Release on the Pressure along the Melting and Sublimation Curves of Ordinary Water Substance (September 2011) (This is a minor revision of the 2008 revised release, which replaced the corresponding release of 1993)
• Revised Release on the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use (September 2009) (This is a minor revision of the 1995 release, which replaced the corresponding release of 1984)
• Revised Release on the Equation of State 2006 for H₂O Ice Ih (September 2009) (This is a minor revision of the 2006 release)
• Release on the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater (September 2008)
• Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance (September 2008)
• Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (The revision only relates to the extension of region 5 to 50 MPa) (August 2007) (This is a revision of the 1997 release, which replaced the corresponding release of 1967).
  NOTE: This release has been supplemented by additional "backward" equations for p(h,s) in Regions 1 and 2, T(p,h), v(p,h), T(p,s), v(p,s) in Region 3, p(h,s) in Region 3 with auxiliary equations for independent variables h and s, and v(p,T) in Region 3.
• Release on the Ionization Constant of H₂O (August 2007)
(This release replaces the corresponding release of 1980)
• Revised Release on Viscosity and Thermal Conductivity of Heavy Water Substance (August 2007) (This is a revision of the 1984 release)
• Revised Release on the IAPS Formulation 1984 for the Thermodynamic Properties of Heavy Water Substance (July 2005) (This is a revision of the 1984 release)
• Release on the Refractive Index of Ordinary Water Substance as a Function of Wavelength, Temperature and Pressure (September 1997) (This release replaces the corresponding release of 1991)
• Release on the Static Dielectric Constant of Ordinary Water Substance for Temperatures from 238 K to 873 K and Pressures up to 1000 MPa (September 1997) (This release replaces the corresponding release of 1977)
• Release: "Surface Tension of Heavy Water Substance" (September 1994) (This is a revision of the 1985 Release)
• Release: "Surface Tension of Ordinary Water Substance" (September 1994) (This is a revision of the 1976 Release)
• Release: "Values of Temperature, Pressure and Density of Ordinary and Heavy Water Substances at their Respective Critical Points" (September 1992) (This is a revision of the 1983 Release)

Supplementary Releases

• Revised Supplementary Release on Properties of Liquid Water at 0.1 MPa (September 2011)
• Supplementary Release on a Computationally Efficient Thermodynamic Formulation for Liquid Water for Oceanographic Use (September 2009)
• Supplementary Release on Backward Equations for Specific Volume as a Function of Pressure and Temperature v(p,T) for Region 3 of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (July 2005)
  NOTE: This Supplementary Release provides additional "backward" equations designed to accompany the IAPWS Industrial Formulation 1997
• Supplementary Release on Backward Equations p(h,s) for Region 3, Equations as a Function of h and s for the Region Boundaries, and an Equation T_sat(h,s) for Region 4 of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (September 2004)
  NOTE: This Supplementary Release provides additional "backward" equations designed to accompany the IAPWS Industrial Formulation 1997
• Revised Supplementary Release on Backward Equations for the Functions T(p,h), v(p,h), and T(p,s), v(p,s) for Region 3 of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (September 2004) (This is a revision of the 2003 Supplementary Release)
  NOTE: This Supplementary Release provides additional "backward" equations designed to accompany the IAPWS Industrial Formulation 1997
• Supplementary Release on Backward Equations for Pressure as a Function of Enthalpy and Entropy p(h,s) to the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (September 2001)
  NOTE: This Supplementary Release provides additional "backward" equations designed to accompany the IAPWS Industrial Formulation 1997
• Revised Supplementary Release on Saturation Properties of Ordinary Water Substance (September 1992) (This is a revision of the 1986 Release)

Guidelines

• Revised Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride (October 2012) (This is a revision of the 2000 Guideline)
• Guideline on a Low-Temperature Extension of the IAPWS-95 Formulation for Water Vapor (October 2012)
• Guideline on an Equation of State for Humid Air in Contact with Seawater and Ice, Consistent with the IAPWS Formulation 2008 for the Thermodynamic Properties of Seawater (July 2010)
• Guideline on the Henry's Constant and Vapor-Liquid Distribution Constant for Gases in H₂O and D₂O at High Temperatures (September 2004) (This guideline replaces a gas solubility guideline issued in 1993 and a distribution constant guideline issued in 1998.)
• Guideline on the Tabular Taylor Series Expansion (TTSE) Method for Calculation of Thermodynamic Properties of Water and Steam Applied to IAPWS-95 as an Example (August 2003)
• Guideline on the Use of Fundamental Physical Constants and Basic Constants of Water (September 2001)
  NOTE: This Guideline is reviewed annually and updated as necessary. Latest update October 2012.
• Guideline on the IAPWS Formulation 2001 for the Thermodynamic Properties of Ammonia-Water Mixtures (September 2001)
• Guideline: "Solubility of Sodium Sulfate in Aqueous Mixtures of Sodium Chloride and Sulfuric Acid from Water to Concentrated Solutions, from 250°C to 350°C" (September 1994)   (This is a revision of the 1990 Guideline)
• Guideline: "Electrolytic Conductivity (Specific Conductance) of Liquid and Dense Supercritical Water from 0°C to 800°C and Pressures up to 1000 MPa" (May 1990)

Advisory Notes

• Advisory Note No. 4: Roles of IAPWS and CIPM Standards for the Density of Water (September 2009)
• Revised Advisory Note No. 3: Thermodynamic Derivatives from IAPWS Formulations (September 2008) (This is a revision of the 2007 Advisory Note)
• Advisory Note No. 2: Role of Various IAPWS Documents Concerning the Thermodynamic Properties of Ordinary Water Substance (September 2004)
  NOTE: This Advisory Note is reviewed annually and updated as necessary. Latest update September 2011.
• Advisory Note No. 1: Uncertainties in Enthalpy for the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use (IAPWS-95) and the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97) (August 2003)

Source for paper copies
Paper copies of IAPWS documents are available from the Executive Secretary, Barry Dooley, bdooley@structint.com. Please include the full title from the list in any request.

This page updated March 5, 2013