# Water (data page)

This page provides supplementary data to the article properties of water.
Further comprehensive authoritative data can be found at the NIST Chemistry WebBook page on thermophysical properties of fluids.

## Structure and properties

Structure and properties :
| Index of refraction, n$_D$ | 1.333 at 20 °C |
| Dielectric constant | 88.00 at 0 °C 86.04 at 5 °C 84.11 at 10 °C 82.22 at 15 °C 80.36 at 20 °C 78.54 at 25 °C 76.75 at 30 °C 75.00 at 35 °C 73.28 at 40 °C 71.59 at 45 °C 69.94 at 50 °C 66.74 at 60 °C 63.68 at 70 °C 60.76 at 80 °C 57.98 at 90 °C 55.33 at 100 °C |
| Bond strength | 492.215 kJ/mol O–H bond dissociation energy |
| Bond length | 95.87 pm (equilibrium) |
| Bond angle | 104.48° (equilibrium) |
| Magnetic susceptibility | −9.04 × 10$^{−6}$ volume SI units |

## Thermodynamic properties

Phase behavior :
| Triple point | 273.16 K (0.01 °C), 611.73 Pa |
| Critical point | 647 K (374 °C), 22.1 MPa |
| Enthalpy change of fusion at 273.15 K, Δ$_{fus}$H | 6.01 kJ/mol |
| Entropy change of fusion at 273.15 K, 1 bar, Δ$_{fus}$S | 22.0 J/(mol·K) |
| Std enthalpy change of vaporization, Δ$_{vap}$H$^o$ | 44.0 kJ/mol |
| Enthalpy change of vaporization at 373.15 K, Δ$_{vap}$H | 40.68 kJ/mol |
| Std entropy change of vaporization, Δ$_{vap}$S$^o$ | 118.89 J/(mol·K) |
| Entropy change of vaporization at 373.15 K, Δ$_{vap}$S | 109.02 J/(mol·K) |
| Enthalpy change of sublimation at 273.15 K, Δ$_{sub}$H | 51.1 kJ/mol |
| Std entropy change of sublimation at 273.15 K, 1 bar, Δ$_{sub}$S | ~144 J/(mol·K) |
| Molal freezing point constant | −1.858 °C kg/mol |
| Molal boiling point constant | 0.512 °C kg/mol |
| Solid properties ||
| Std enthalpy change of formation, Δ$_f$H$^o$$_{solid}$ | −291.83 kJ/mol |
| Standard molar entropy, S$^o$$_{solid}$ | 41 J/(mol K) |
| Heat capacity, c$_p$ | 12.2 J/(mol K) at −200 °C 15.0 J/(mol K) at −180 °C 17.3 J/(mol K) at −160 °C 19.8 J/(mol K) at −140 °C 24.8 J/(mol K) at −100 °C 29.6 J/(mol K) at −60 °C 32.77 J/(mol K) at −38.3 °C 33.84 J/(mol K) at −30.6 °C 35.20 J/(mol K) at −20.8 °C 36.66 J/(mol K) at −11.0 °C 37.19 J/(mol K) at −4.9 °C 37.84 J/(mol K) at −2.2 °C |
| Liquid properties ||
| Std enthalpy change of formation, Δ$_f$H$^o$$_{liquid}$ | −285.83 kJ/mol |
| Standard molar entropy, S$^o$$_{liquid}$ | 69.95 J/(mol K) |
| Heat capacity, c$_p$ | 75.97 J/(mol K) and 4.2176 J/(g·K) at 0 °C 75.52 J/(mol K) and 4.1921 J/(g·K) at 10 °C 75.33 J/(mol K) and 4.1818 J/(g·K) at 20 °C 75.28 J/(mol K) and 4.1787 J/(g·K) at 25 °C 75.26 J/(mol K) and 4.1784 J/(g·K) at 30 °C 75.26 J/(mol K) and 4.1785 J/(g·K) at 40 °C 75.30 J/(mol K) and 4.1806 J/(g·K) at 50 °C 75.37 J/(mol K) and 4.1843 J/(g·K) at 60 °C 75.46 J/(mol K) and 4.1895 J/(g·K) at 70 °C 75.58 J/(mol K) and 4.1963 J/(g·K) at 80 °C 75.74 J/(mol K) and 4.2050 J/(g·K) at 90 °C 75.94 J/(mol K) and 4.2159 J/(g·K) at 100 °C |
| Gas properties ||
| Std enthalpy change of formation, Δ$_f$H$^o$$_{gas}$ | −241.83 kJ/mol |
| Standard molar entropy, S$^o$$_{gas}$ | 188.84 J/(mol K) |
| Heat capacity, c$_p$ | 36.5 J/(mol K) at 100 °C 36.1 J/(mol K) at 200 °C 36.2 J/(mol K) at 400 °C 37.9 J/(mol K) at 700 °C 41.4 J/(mol K) at 1000 °C |
| Heat capacity, c$_v$ | 27.5 J/(mol K) at 100 °C 27.6 J/(mol K) at 200 °C 27.8 J/(mol K) at 400 °C 29.5 J/(mol K) at 700 °C 33.1 J/(mol K) at 1000 °C |
| Heat capacity ratio, γ = c$_p$/c$_v$ | 1.324 at 100 °C 1.310 at 200 °C 1.301 at 400 °C 1.282 at 700 °C 1.252 at 1000 °C |
| van der Waals' constants | a = 553.6 L$^2$ kPa/mol$^2$ b = 0.03049 L/mol |

## Liquid physical properties

Velocity of sound in water :
| c in distilled water at 25 °C | 1498 m/s |
| c at other temperatures | 1403 m/s at 0 °C 1427 m/s at 5 °C 1447 m/s at 10 °C 1481 m/s at 20 °C 1507 m/s at 30 °C 1526 m/s at 40 °C 1541 m/s at 50 °C 1552 m/s at 60 °C 1555 m/s at 70 °C 1555 m/s at 80 °C 1550 m/s at 90 °C 1543 m/s at 100 °C |
| Density ||
| 0.983854 g/cm$^3$ at −30 °C | 0.99221 g/cm$^3$ at 40 °C |
| 0.993547 g/cm$^3$ at −20 °C | 0.99022 g/cm$^3$ at 45 °C |
| 0.998117 g/cm$^3$ at −10 °C | 0.98804 g/cm$^3$ at 50 °C |
| 0.9998395 g/cm$^3$ at 0 °C | 0.98570 g/cm$^3$ at 55 °C |
| 0.999972 g/cm$^3$ at 3.984 °C |
| 0.9999720 g/cm$^3$ at 4 °C | 0.98321 g/cm$^3$ at 60 °C |
| 0.99996 g/cm$^3$ at 5 °C | 0.98056 g/cm$^3$ at 65 °C |
| 0.9997026 g/cm$^3$ at 10 °C | 0.97778 g/cm$^3$ at 70 °C |
| 0.9991026 g/cm$^3$ at 15 °C | 0.97486 g/cm$^3$ at 75 °C |
| 0.9982071 g/cm$^3$ at 20 °C | 0.97180 g/cm$^3$ at 80 °C |
| 0.9977735 g/cm$^3$ at 22 °C | 0.96862 g/cm$^3$ at 85 °C |
| 0.9970479 g/cm$^3$ at 25 °C | 0.96531 g/cm$^3$ at 90 °C |
| 0.9956502 g/cm$^3$ at 30 °C | 0.96189 g/cm$^3$ at 95 °C |
| 0.99403 g/cm$^3$ at 35 °C | 0.95835 g/cm$^3$ at 100 °C |
| The values below 0 °C refer to supercooled water. ||
| Viscosity ||
| 1.7921 mPa·s (cP) at 0 °C | 0.5494 mPa·s at 50 °C |
| 1.5188 mPa·s at 5 °C | 0.5064 mPa·s at 55 °C |
| 1.3077 mPa·s at 10 °C | 0.4688 mPa·s at 60 °C |
| 1.1404 mPa·s at 15 °C | 0.4355 mPa·s at 65 °C |
| 1.0050 mPa·s at 20 °C | 0.4061 mPa·s at 70 °C |
| 0.8937 mPa·s at 25 °C | 0.3799 mPa·s at 75 °C |
| 0.8007 mPa·s at 30 °C | 0.3635 mPa·s at 80 °C |
| 0.7225 mPa·s at 35 °C | 0.3355 mPa·s at 85 °C |
| 0.6560 mPa·s at 40 °C | 0.3165 mPa·s at 90 °C |
| 0.5988 mPa·s at 45 °C | 0.2994 mPa·s at 95 °C |
| | 0.2838 mPa·s at 100 °C |
| Surface tension ||
| 75.64 dyn/cm at 0 °C | 69.56 dyn/cm at 40 °C |
| 74.92 dyn/cm at 5 °C | 68.74 dyn/cm at 45 °C |
| 74.22 dyn/cm at 10 °C | 67.91 dyn/cm at 50 °C |
| 73.49 dyn/cm at 15 °C | 66.18 dyn/cm at 60 °C |
| 72.75 dyn/cm at 20 °C | 64.42 dyn/cm at 70 °C |
| 71.97 dyn/cm at 25 °C | 62.61 dyn/cm at 80 °C |
| 71.18 dyn/cm at 30 °C | 60.75 dyn/cm at 90 °C |
| 70.38 dyn/cm at 35 °C | 58.85 dyn/cm at 100 °C |
Electrical conductivity of highly purified water at saturation pressure :
| Temperature, °C | Conductivity, μS/m |
| 0.01 | 1.15 |
| 25 | 5.50 |
| 100 | 76.5 |
| 200 | 299 |
| 300 | 241 |

## Water/steam equilibrium properties

Vapor pressure formula for steam in equilibrium with liquid water:
    $\log _{10}P=A-{\frac {B}{T-C}},$
where P is equilibrium vapor pressure in kPa, and T is temperature in kelvins.
For T = 273 K to 333 K: A = 7.2326; B = 1750.286; C = 38.1.
For T = 333 K to 423 K: A = 7.0917; B = 1668.21; C = 45.1.
Steam table :
| Temperature (°C) | Pressure (kPa) | H of liquid (J/g) | Δ$_{vap}$H (J/g) | W$_{vap}$ (J/g) | ρ of vapor (kg/m$^3$) |
| 0 | 0.612 | 0.00 | 2496.5 | 126.0 | 0.004855 |
| 10 | 1.227 | 42.0 | 2473.5 | 130.5 | 0.009498 |
| 20 | 2.336 | 83.8 | 2450.9 | 135.1 | 0.01728 |
| 30 | 4.242 | 125.6 | 2427.9 | 139.7 | 0.03037 |
| 40 | 7.370 | 167.2 | 2404.9 | 144.2 | 0.05107 |
| 50 | 12.33 | 209.0 | 2381.4 | 148.7 | 0.08275 |
| 60 | 19.90 | 250.8 | 2357.6 | 153.0 | 0.1300 |
| 70 | 31.15 | 292.7 | 2332.9 | 157.3 | 0.1979 |
| 80 | 46.12 | 334.6 | 2307.7 | 161.5 | 0.2930 |
| 90 | 70.10 | 376.6 | 2282.6 | 165.5 | 0.4232 |
| 100 | 101.32 | 419.0 | 2256.3 | 169.4 | 0.5974 |
| 110 | 143.27 | 460.8 | 2229.5 | 173.1 | 0.8264 |
| 120 | 198.50 | 503.2 | 2201.4 | 176.7 | 1.121 |
| 130 | 270.13 | 545.8 | 2172.5 | 180.2 | 1.497 |
| 140 | 361.4 | 588.5 | 2142.8 | 183.2 | 1.967 |
| 150 | 476.0 | 631.5 | 2111.8 | 186.1 | 2.548 |
| 160 | 618.1 | 674.7 | 2080.0 | 188.7 | 3.263 |
| 170 | 792.0 | 718.5 | 2047.0 | 190.6 | 4.023 |
| 180 | 1002.7 | 762.5 | 2012.2 | 192.8 | 5.165 |
| 190 | 1254.9 | 807.0 | 1975.8 | 194.5 | 6.402 |
| 200 | 1554.3 | 851.9 | 1937.3 | 195.6 | 7.868 |
| 210 | 1907.9 | 897.5 | 1897.5 | 196.3 | 9.606 |
| 221.1 | 2369.8 | 948.5 | 1850.2 | 196.6 | 11.88 |
| 229.4 | 2769.6 | 987.9 | 1812.5 | 196.2 | 13.87 |
| 240.6 | 3381.1 | 1040.6 | 1759.4 | 195.1 | 16.96 |
| 248.9 | 3904.1 | 1080.3 | 1715.8 | 193.7 | 19.66 |
| 260.0 | 4695.9 | 1134.8 | 1653.9 | 190.8 | 23.84 |
| 271.1 | 5603.4 | 1195.9 | 1586.5 | 186.9 | 28.83 |
| 279.4 | 6366.5 | 1240.7 | 1532.5 | 183.3 | 33.18 |
| 290.6 | 7506.2 | 1302.3 | 1456.3 | 177.4 | 39.95 |
| 298.9 | 8463.9 | 1350.0 | 1394.8 | 172.2 | 45.93 |
| 310.0 | 9878.0 | 1415.7 | 1307.7 | 164.2 | 55.25 |
| 321.1 | 11461 | 1483.9 | 1212.7 | 154.5 | 66.58 |
| 329.4 | 12785 | 1537.9 | 1133.2 | 145.6 | 76.92 |
| 340.6 | 14727 | 1617.9 | 1007.6 | 130.9 | 94.25 |
| 348.9 | 16331 | 1687.0 | 892.0 | 117.0 | 111.5 |
| 360.0 | 18682 | 1797.0 | 694.0 | 91.0 | 145.3 |
| 371.1 | 21349 | 1968.3 | 365.0 | 47.0 | 214.5 |
| 374.4 | 22242 | 2151.2 | 0 | 0 | 306.8 |
| Temperature (°C) | Pressure (kPa) | H of liquid (J/g) | Δ$_{vap}$H (J/g) | W$_{vap}$ (J/g) | ρ of vapor (kg/m$^3$) |
Data in the table above is given for water–steam equilibria at various temperatures over the entire temperature range at which liquid water can exist. Pressure of the equilibrium is given in the second column in kPa. The third column is the heat content of each gram of the liquid phase relative to water at 0 °C. The fourth column is the heat of vaporization of each gram of liquid that changes to vapor. The fifth column is the work PΔV done by each gram of liquid that changes to vapor. The sixth column is the density of the vapor.

## Melting point of ice at various pressures

Data obtained from CRC Handbook of Chemistry and Physics 44th ed., p. 2390.
| Pressure kPa | Temp. °C |
| 101.325 | 0.0 |
| 32950 | −2.5 |
| 60311 | −5.0 |
| 87279 | −7.5 |
| 113267 | −10.0 |
| 138274 | −12.5 |
| 159358 | −15.0 |
| 179952 | −17.5 |
| 200251 | −20.0 |
| 215746 | −22.1 |

## Table of various forms of ice

Properties of various forms of ice :
| Ice form | Density g/cm$^3$ | Crystal structure | Triple points | TP temp °C | TP pressure MPa |
| I$_h$ | 0.92 | hexagonal | Lq, Vap, I$_h$ | 0.01 | 0.000612 |
| I$_h$ | 0.92 | hexagonal | Lq, I$_h$, III | −22.0 | 207.5 |
| I$_h$ | 0.92 | hexagonal | I$_h$, II, III | −34.7 | 212.9 |
| I$_c$ | 0.92 | cubic | | | |
| II | 1.17 | rhombohedral | I$_h$, II, III | −34.7 | 212.9 |
| II | 1.17 | rhombohedral | II, III, V | −24.3 | 344.3 |
| II | 1.17 | rhombohedral | II, V, VI | −55 (est) | 620 |
| III | 1.14 | tetragonal | Lq, I$_h$, III | −22.0 | 207.5 |
| III | 1.14 | tetragonal | Lq, III, V | −17 | 346.3 |
| III | 1.14 | tetragonal | I$_h$, II, III | −34.7 | 212.9 |
| III | 1.14 | tetragonal | II, III, V | −24.3 | 344.3 |
| IV | 1.27 | rhombohedral | | | |
| V | 1.23 | monoclinic | Lq, III, V | −17 | 346.3 |
| V | 1.23 | monoclinic | Lq, V, VI | 0.16 | 625.9 |
| V | 1.23 | monoclinic | II, III, V | −24.3 | 344.3 |
| V | 1.23 | monoclinic | II, V, VI | −55 (est) | 620 |
| VI | 1.31 | tetragonal | Lq, V, VI | 0.16 | 625.9 |
| VI | 1.31 | tetragonal | Lq, VI, VII | 81.6 | 2200 |
| VI | 1.31 | tetragonal | II, V, VI | −55 (est) | 620 |
| VI | 1.31 | tetragonal | VI, VII, VIII | ≈5 | 2100 |
| VII | 1.50 | cubic | Lq, VI, VII | 81.6 | 2200 |
| VII | 1.50 | cubic | VI, VII, VIII | ≈5 | 2100 |
| VII | 1.50 | cubic | VII, VIII, X | −173 | 62000 |
| VIII | 1.46 | tetragonal | VI, VII, VIII | ≈5 | 2100 |
| VIII | 1.46 | tetragonal | VII, VIII, X | −173 | 62000 |
| IX | 1.16 | tetragonal | | | |
| X | 2.46 | cubic | VII, VIII, X | −173 | 62000 |
| XI$^‡$ | 0.92 | orthorhombic | Vap, I$_h$, XI | −201.5 | 0 (expected) |
| XII | 1.29 | tetragonal | | | |
| XIII | 1.23 | monoclinic | | | |
| XIV | 1.29 | orthorhombic | | | |
$^‡$Ice XI triple point is theoretical and has never been obtained

## Water with dissolved NaCl

Properties of water–NaCl mixtures :
| NaCl, wt% | T$_{eq}$, °C | ρ, g/cm$^3$ | n | η, mPa·s |
| 0 | 0 | 0.99984 | 1.333 | 1.002 |
| 0.5 | −0.3 | 1.0018 | 1.3339 | 1.011 |
| 1 | −0.59 | 1.0053 | 1.3347 | 1.02 |
| 2 | −1.19 | 1.0125 | 1.3365 | 1.036 |
| 3 | −1.79 | 1.0196 | 1.3383 | 1.052 |
| 4 | −2.41 | 1.0268 | 1.34 | 1.068 |
| 5 | −3.05 | 1.034 | 1.3418 | 1.085 |
| 6 | −3.7 | 1.0413 | 1.3435 | 1.104 |
| 7 | −4.38 | 1.0486 | 1.3453 | 1.124 |
| 8 | −5.08 | 1.0559 | 1.347 | 1.145 |
| 9 | −5.81 | 1.0633 | 1.3488 | 1.168 |
| 10 | −6.56 | 1.0707 | 1.3505 | 1.193 |
| 12 | −8.18 | 1.0857 | 1.3541 | 1.25 |
| 14 | −9.94 | 1.1008 | 1.3576 | 1.317 |
| 16 | −11.89 | 1.1162 | 1.3612 | 1.388 |
| 18 | −14.04 | 1.1319 | 1.3648 | 1.463 |
| 20 | −16.46 | 1.1478 | 1.3684 | 1.557 |
| 22 | −19.18 | 1.164 | 1.3721 | 1.676 |
| 23.3 | −21.1 | | | |
| 23.7 | −17.3 | | | |
| 24.9 | −11.1 | | | |
| 26.1 | −2.7 | | | |
| 26.28 | 0 | | | |
| 26.32 | 10 | | | |
| 26.41 | 20 | | | |
| 26.45 | 25 | | | |
| 26.52 | 30 | | | |
| 26.67 | 40 | | | |
| 26.84 | 50 | | | |
| 27.03 | 60 | | | |
| 27.25 | 70 | | | |
| 27.5 | 80 | | | |
| 27.78 | 90 | | | |
| 28.05 | 100 | | | |
Note: ρ is density, n is refractive index at 589 nm, and η is viscosity, all at 20 °C; T$_{eq}$ is the equilibrium temperature between two phases: ice/liquid solution for T$_{eq}$ < 0–0.1 °C and NaCl/liquid solution for T$_{eq}$ above 0.1 °C.

## Self-ionization

| °C | °C | −35 | 0 | 25 | 60 | 300 (~50 MPa) |
| pK$_w$ | pK$_w$ | 17 | 14.9 | 14.0 | 13.0 | 12 |
    $pK_{w}=-\log([\mathrm {H} ^{+}][\mathrm {OH} ^{-}])$

## Spectral data

UV-Vis :
| λ$_{max}$ | ? nm |
| Extinction coefficient, ε | ? |
| IR ||
| Major absorption bands | vapor:ν$_1$ = 3657.05,ν$_2$ = 1594.75,ν$_3$ = 3755.93cm$^{−1}$ liquid:ν$_1$ = 3280,ν$_2$ = 1644,ν$_3$ = 3490cm$^{−1}$ hexagonal ice:ν$_1$ = 3085,ν$_2$ = 1650,ν$_3$ = 3220cm$^{−1}$ |
| NMR ||
| Proton NMR | 4.79 ppm in D$_2$O ; 1.56 ppm in CDCl$_3$ ; 0.40 ppm in C$_6$D$_6$ ; 4.87 in CD$_3$OD |
| Carbon-13 NMR | N/A |
| Other NMR data | |
| MS ||
| Masses of main fragments | |

## Self-diffusion coefficients

Experimental self-diffusion coefficients at various temperatures :
| Temperature in °C | Coefficients in 10$^{−9}$ m$^2$/s |
| 0 | 1.099 |
| 1 | 1.138 |
| 4 | 1.261 |
| 5 | 1.303 |
| 10 | 1.525 |
| 15 | 1.765 |
| 20 | 2.023 |
| 25 | 2.299 |
| 30 | 2.594 |
| 35 | 2.907 |
| 40 | 3.238 |
| 45 | 3.588 |
| 50 | 3.956 |
| 56 | 4.423 |
| 60 | 4.748 |
| 70 | 5.615 |
| 80 | 6.557 |
| 90 | 7.574 |
| 100 | 8.667 |

## Additional data translated from German "Wasser (Stoffdaten)" page

The data that follows was copied and translated from the German language Wikipedia version of this page (which has moved to here). It provides supplementary physical, thermodynamic, and vapor pressure data, some of which is redundant with data in the tables above, and some of which is additional.

### Physical and thermodynamic tables

In the following tables, values are temperature-dependent and to a lesser degree pressure-dependent, and are arranged by state of aggregation (s = solid, lq = liquid, g = gas), which are clearly a function of temperature and pressure. All of the data were computed from data given in "Formulation of the Thermodynamic Properties of Ordinary Water Substance for Scientific and General Use" (IAPWS , 1984) (obsolete as of 1995). This applies to:
* T – temperature in degrees Celsius
* V – specific volume in cubic decimeters per kilogram (1 dm$^3$ is equivalent to 1 liter)
* H – specific enthalpy in kilojoules per kilogram
* U – specific internal energy in kilojoules per kilogram
* S – specific entropy in kilojoules per kilogram-kelvin
* c$_p$ – specific heat capacity at constant pressure in kilojoules per kilogram-kelvin
* γ – Thermal expansion coefficient as 10$^{−3}$ per kelvin
* λ – Heat conductivity in milliwatts per meter-kelvin
* η – Viscosity in micropascal-seconds (1 cP = 1000 μPa·s)
* σ – surface tension in millinewtons per meter (equivalent to dyn/cm)

#### Standard conditions

In the following table, material data are given for standard pressure of 0.1 MPa (equivalent to 1 bar). Up to 99.63 °C (the boiling point of water at 0.1 MPa), at this pressure water exists as a liquid. Above that, it exists as water vapor. Note that the boiling point of 100.0 °C is at a pressure of 0.101325 MPa (1 atm), which is the average atmospheric pressure.
Water/steam data table at standard pressure (0.1 MPa) :
| T °C | T °C | V dm$^3$/kg | H kJ/kg | U kJ/kg | S kJ/(kg·K) | c$_p$ kJ/(kg·K) | γ 10$^{−3}$/K | λ mW / (m·K) | η μPa·s | σ $^‡$ mN/m |
| 0 | lq | 1.0002 | 0.06 | −0.04 | −0.0001 | 4.228 | −0.080 | 561.0 | 1792 | 75.65 |
| 5 | lq | 1.0000 | 21.1 | 21.0 | 0.076 | 4.200 | 0.011 | 570.6 | 1518 | 74.95 |
| 10 | lq | 1.0003 | 42.1 | 42.0 | 0.151 | 4.188 | 0.087 | 580.0 | 1306 | 74.22 |
| 15 | lq | 1.0009 | 63.0 | 62.9 | 0.224 | 4.184 | 0.152 | 589.4 | 1137 | 73.49 |
| 20 | lq | 1.0018 | 83.9 | 83.8 | 0.296 | 4.183 | 0.209 | 598.4 | 1001 | 72.74 |
| 25 | lq | 1.0029 | 104.8 | 104.7 | 0.367 | 4.183 | 0.259 | 607.2 | 890.4 | 71.98 |
| 30 | lq | 1.0044 | 125.8 | 125.7 | 0.437 | 4.183 | 0.305 | 615.5 | 797.7 | 71.20 |
| 35 | lq | 1.0060 | 146.7 | 146.6 | 0.505 | 4.183 | 0.347 | 623.3 | 719.6 | 70.41 |
| 40 | lq | 1.0079 | 167.6 | 167.5 | 0.572 | 4.182 | 0.386 | 630.6 | 653.3 | 69.60 |
| 45 | lq | 1.0099 | 188.5 | 188.4 | 0.638 | 4.182 | 0.423 | 637.3 | 596.3 | 68.78 |
| 50 | lq | 1.0121 | 209.4 | 209.3 | 0.704 | 4.181 | 0.457 | 643.6 | 547.1 | 67.95 |
| 60 | lq | 1.0171 | 251.2 | 251.1 | 0.831 | 4.183 | 0.522 | 654.4 | 466.6 | 66.24 |
| 70 | lq | 1.0227 | 293.1 | 293.0 | 0.955 | 4.187 | 0.583 | 663.1 | 404.1 | 64.49 |
| 80 | lq | 1.0290 | 335.0 | 334.9 | 1.075 | 4.194 | 0.640 | 670.0 | 354.5 | 62.68 |
| 90 | lq | 1.0359 | 377.0 | 376.9 | 1.193 | 4.204 | 0.696 | 675.3 | 314.6 | 60.82 |
| 99.63 | lq | 1.0431 | 417.5 | 417.4 | 1.303 | 4.217 | 0.748 | 679.0 | 283.0 | 58.99 |
| 99.63 | g | 1694.3 | 2675 | 2505 | 7.359 | 2.043 | 2.885 | 25.05 | 12.26 | – |
| 100 | g | 1696.1 | 2675 | 2506 | 7.361 | 2.042 | 2.881 | 25.08 | 12.27 | 58.92 |
| 200 | g | 2172.3 | 2874 | 2657 | 7.833 | 1.975 | 2.100 | 33.28 | 16.18 | 37.68 |
| 300 | g | 2638.8 | 3073 | 2810 | 8.215 | 2.013 | 1.761 | 43.42 | 20.29 | 14.37 |
| 500 | g | 3565.5 | 3488 | 3131 | 8.834 | 2.135 | 1.297 | 66.970 | 28.57 | – |
| 750 | g | 4721.0 | 4043 | 3571 | 9.455 | 2.308 | 0.978 | 100.30 | 38.48 | – |
| 1000 | g | 5875.5 | 4642 | 4054 | 9.978 | 2.478 | 0.786 | 136.3 | 47.66 | – |
| $^‡$ The values for surface tension for the liquid section of the table are for a liquid/air interface. Values for the gas section of the table are for a liquid/saturated steam interface. |||||||||||

#### Triple point

In the following table, material data are given with a pressure of 611.7 Pa (equivalent to 0.006117 bar). Up to a temperature of 0.01 °C, the triple point of water, water normally exists as ice, except for supercooled water, for which one data point is tabulated here. At the triple point, ice can exist together with both liquid water and vapor. At higher temperatures, the data are for water vapor only.
Water/steam data table at triple point pressure (0.0006117 MPa) :
| T °C | T °C | V dm$^3$/kg | H kJ/kg | U kJ/kg | S kJ/(kg·K) | c$_p$ kJ/(kg·K) | γ 10$^{−3}$/K | λ mW / (m·K) | η μPa·s |
| 0 | lq | 1.0002 | −0.04 | −0.04 | −0.0002 | 4.339 | −0.081 | 561.0 | 1792 |
| 0.01 | s | 1.0908 | −333.4 | −333.4 | −1.221 | 1.93 | 0.1 | 2180 | – |
| 0.01 | lq | 1.0002 | 0.0 | 0 | 0 | 4.229 | −0.080 | 561.0 | 1791 |
| 0.01 | g | 205986 | 2500 | 2374 | 9.154 | 1.868 | 3.672 | 17.07 | 9.22 |
| 5 | g | 209913 | 2509 | 2381 | 9.188 | 1.867 | 3.605 | 17.33 | 9.34 |
| 10 | g | 213695 | 2519 | 2388 | 9.222 | 1.867 | 3.540 | 17.60 | 9.46 |
| 15 | g | 217477 | 2528 | 2395 | 9.254 | 1.868 | 3.478 | 17.88 | 9.59 |
| 20 | g | 221258 | 2537 | 2402 | 9.286 | 1.868 | 3.417 | 18.17 | 9.73 |
| 25 | g | 225039 | 2547 | 2409 | 9.318 | 1.869 | 3.359 | 18.47 | 9.87 |
| 30 | g | 228819 | 2556 | 2416 | 9.349 | 1.869 | 3.304 | 18.78 | 10.02 |
| 35 | g | 232598 | 2565 | 2423 | 9.380 | 1.870 | 3.249 | 19.10 | 10.17 |
| 40 | g | 236377 | 2575 | 2430 | 9.410 | 1.871 | 3.197 | 19.43 | 10.32 |
| 45 | g | 240155 | 2584 | 2437 | 9.439 | 1.872 | 3.147 | 19.77 | 10.47 |
| 50 | g | 243933 | 2593 | 2444 | 9.469 | 1.874 | 3.098 | 20.11 | 10.63 |
| 60 | g | 251489 | 2612 | 2459 | 9.526 | 1.876 | 3.004 | 20.82 | 10.96 |
| 70 | g | 259043 | 2631 | 2473 | 9.581 | 1.880 | 2.916 | 21.56 | 11.29 |
| 80 | g | 266597 | 2650 | 2487 | 9.635 | 1.883 | 2.833 | 22.31 | 11.64 |
| 90 | g | 274150 | 2669 | 2501 | 9.688 | 1.887 | 2.755 | 23.10 | 11.99 |
| 100 | g | 281703 | 2688 | 2515 | 9.739 | 1.891 | 2.681 | 23.90 | 12.53 |
| 200 | g | 357216 | 2879 | 2661 | 10.194 | 1.940 | 2.114 | 32.89 | 16.21 |
| 300 | g | 432721 | 3076 | 2811 | 10.571 | 2.000 | 1.745 | 43.26 | 20.30 |
| 500 | g | 583725 | 3489 | 3132 | 11.188 | 2.131 | 1.293 | 66.90 | 28.57 |
| 750 | g | 772477 | 4043 | 3571 | 11.808 | 2.307 | 0.977 | 100.20 | 38.47 |
| 1000 | g | 961227 | 4642 | 4054 | 12.331 | 2.478 | 0.785 | 136.30 | 47.66 |

### Saturated vapor pressure

The following table is based on different, complementary sources and approximation formulas, whose values are of various quality and accuracy. The values in the temperature range of −100 °C to 100 °C were inferred from D. Sunday (1982) and are quite uniform and exact. The values in the temperature range of the boiling point of water up to the critical point (100 °C to 374 °C) are drawn from different sources and are substantially less accurate; hence they should be used only as approximate values.
To use the values correctly, consider the following points:
* The values apply only to smooth interfaces and in the absence other gases or gas mixtures such as air. Hence they apply only to pure phases and need a correction factor for systems in which air is present.
* The values were not computed according formulas widely used in the US, but using somewhat more exact formulas (see below), which can also be used to compute further values in the appropriate temperature ranges.
* The saturated vapor pressure over water in the temperature range of −100 °C to −50 °C is only extrapolated [Translator's note: Supercooled liquid water is not known to exist below −42 °C].
* The values have various units (Pa, hPa or bar), which must be considered when reading them.

#### Formulas

The table values for −100 °C to 100 °C were computed by the following formulas, where T is in kelvins and vapor pressures, P$_w$ and P$_i$, are in pascals.
Over liquid water
    log$_e$(P$_w$) = −6094.4642 T$^{−1}$ + 21.1249952 − 2.724552×10$^{−2}$ T + 1.6853396×10$^{−5}$ T$^2$ + 2.4575506 log$_e$(T)
For temperature range: 173.15 K to 373.15 K or equivalently −100 °C to 100 °C
Over ice
    log$_e$(P$_i$) = −5504.4088 T$^{−1}$ − 3.5704628 − 1.7337458×10$^{−2}$ T + 6.5204209×10$^{−6}$ T$^2$ + 6.1295027 log$_e$(T)
For temperature range: 173.15 K to 273.15 K or equivalently −100 °C to 0 °C
At triple point
An important basic value, which is not registered in the table, is the saturated vapor pressure at the triple point of water. The internationally accepted value according to measurements of Guildner, Johnson and Jones (1976) amounts to:
    P$_w$(t$_{tp}$ = 0.01 °C) = 611.657 Pa ± 0.010 Pa at (1 − α) = 99%
Values of saturated vapor pressure of water :
| Temp. T in °C | P$_i$(T) over ice in Pa | P$_w$(T) over water in Pa | Temp. T in °C | P$_w$(T) over water in hPa | Temp. T in °C | P(T) in bar | Temp. T in °C | P(T) in bar | Temp. T in °C | P(T) in bar |
| −100 | 0.0013957 | 0.0036309 | 0 | 6.11213 | 100 | 1.01 | 200 | 15.55 | 300 | 85.88 |
| −99 | 0.0017094 | 0.0044121 | 1 | 6.57069 | 101 | 1.05 | 201 | 15.88 | 301 | 87.09 |
| −98 | 0.0020889 | 0.0053487 | 2 | 7.05949 | 102 | 1.09 | 202 | 16.21 | 302 | 88.32 |
| −97 | 0.0025470 | 0.0064692 | 3 | 7.58023 | 103 | 1.13 | 203 | 16.55 | 303 | 89.57 |
| −96 | 0.0030987 | 0.0078067 | 4 | 8.13467 | 104 | 1.17 | 204 | 16.89 | 304 | 90.82 |
| −95 | 0.0037617 | 0.0093996 | 5 | 8.72469 | 105 | 1.21 | 205 | 17.24 | 305 | 92.09 |
| −94 | 0.0045569 | 0.011293 | 6 | 9.35222 | 106 | 1.25 | 206 | 17.60 | 306 | 93.38 |
| −93 | 0.0055087 | 0.013538 | 7 | 10.0193 | 107 | 1.30 | 207 | 17.96 | 307 | 94.67 |
| −92 | 0.0066455 | 0.016195 | 8 | 10.7280 | 108 | 1.34 | 208 | 18.32 | 308 | 95.98 |
| −91 | 0.0080008 | 0.019333 | 9 | 11.4806 | 109 | 1.39 | 209 | 18.70 | 309 | 97.31 |
| −90 | 0.0096132 | 0.023031 | 10 | 12.2794 | 110 | 1.43 | 210 | 19.07 | 310 | 98.65 |
| −89 | 0.011528 | 0.027381 | 11 | 13.1267 | 111 | 1.48 | 211 | 19.46 | 311 | 100.00 |
| −88 | 0.013797 | 0.032489 | 12 | 14.0251 | 112 | 1.53 | 212 | 19.85 | 312 | 101.37 |
| −87 | 0.016482 | 0.038474 | 13 | 14.9772 | 113 | 1.58 | 213 | 20.25 | 313 | 102.75 |
| −86 | 0.019653 | 0.045473 | 14 | 15.9856 | 114 | 1.64 | 214 | 20.65 | 314 | 104.15 |
| −85 | 0.02339 | 0.053645 | 15 | 17.0532 | 115 | 1.69 | 215 | 21.06 | 315 | 105.56 |
| −84 | 0.027788 | 0.063166 | 16 | 18.1829 | 116 | 1.75 | 216 | 21.47 | 316 | 106.98 |
| −83 | 0.032954 | 0.074241 | 17 | 19.3778 | 117 | 1.81 | 217 | 21.89 | 317 | 108.43 |
| −82 | 0.039011 | 0.087101 | 18 | 20.6409 | 118 | 1.86 | 218 | 22.32 | 318 | 109.88 |
| −81 | 0.046102 | 0.10201 | 19 | 21.9757 | 119 | 1.93 | 219 | 22.75 | 319 | 111.35 |
| −80 | 0.054388 | 0.11925 | 20 | 23.3854 | 120 | 1.99 | 220 | 23.19 | 320 | 112.84 |
| −79 | 0.064057 | 0.13918 | 21 | 24.8737 | 121 | 2.05 | 221 | 23.64 | 321 | 114.34 |
| −78 | 0.075320 | 0.16215 | 22 | 26.4442 | 122 | 2.12 | 222 | 24.09 | 322 | 115.86 |
| −77 | 0.088419 | 0.18860 | 23 | 28.1006 | 123 | 2.18 | 223 | 24.55 | 323 | 117.39 |
| −76 | 0.10363 | 0.21901 | 24 | 29.8470 | 124 | 2.25 | 224 | 25.02 | 324 | 118.94 |
| −75 | 0.12127 | 0.25391 | 25 | 31.6874 | 125 | 2.32 | 225 | 25.49 | 325 | 120.51 |
| −74 | 0.14168 | 0.29390 | 26 | 33.6260 | 126 | 2.40 | 226 | 25.98 | 326 | 122.09 |
| −73 | 0.16528 | 0.33966 | 27 | 35.6671 | 127 | 2.47 | 227 | 26.46 | 327 | 123.68 |
| −72 | 0.19252 | 0.39193 | 28 | 37.8154 | 128 | 2.55 | 228 | 26.96 | 328 | 125.30 |
| −71 | 0.22391 | 0.45156 | 29 | 40.0754 | 129 | 2.62 | 229 | 27.46 | 329 | 126.93 |
| −70 | 0.26004 | 0.51948 | 30 | 42.4520 | 130 | 2.70 | 230 | 27.97 | 330 | 128.58 |
| −69 | 0.30156 | 0.59672 | 31 | 44.9502 | 131 | 2.78 | 231 | 28.48 | 331 | 130.24 |
| −68 | 0.34921 | 0.68446 | 32 | 47.5752 | 132 | 2.87 | 232 | 29.01 | 332 | 131.92 |
| −67 | 0.40383 | 0.78397 | 33 | 50.3322 | 133 | 2.95 | 233 | 29.54 | 333 | 133.62 |
| −66 | 0.46633 | 0.89668 | 34 | 53.2267 | 134 | 3.04 | 234 | 30.08 | 334 | 135.33 |
| −65 | 0.53778 | 1.0242 | 35 | 56.2645 | 135 | 3.13 | 235 | 30.62 | 335 | 137.07 |
| −64 | 0.61933 | 1.1682 | 36 | 59.4513 | 136 | 3.22 | 236 | 31.18 | 336 | 138.82 |
| −63 | 0.71231 | 1.3306 | 37 | 62.7933 | 137 | 3.32 | 237 | 31.74 | 337 | 140.59 |
| −62 | 0.81817 | 1.5136 | 38 | 66.2956 | 138 | 3.42 | 238 | 32.31 | 338 | 142.37 |
| −61 | 0.93854 | 1.7195 | 39 | 69.9675 | 139 | 3.51 | 239 | 32.88 | 339 | 144.18 |
| −60 | 1.0753 | 1.9509 | 40 | 73.8127 | 140 | 3.62 | 240 | 33.47 | 340 | 146.00 |
| −59 | 1.2303 | 2.2106 | 41 | 77.8319 | 141 | 3.72 | 241 | 34.06 | 341 | 147.84 |
| −58 | 1.4060 | 2.5018 | 42 | 82.0536 | 142 | 3.82 | 242 | 34.66 | 342 | 149.71 |
| −57 | 1.6049 | 2.8277 | 43 | 86.4633 | 143 | 3.93 | 243 | 35.27 | 343 | 151.58 |
| −56 | 1.8296 | 3.1922 | 44 | 91.0757 | 144 | 4.04 | 244 | 35.88 | 344 | 153.48 |
| −55 | 2.0833 | 3.5993 | 45 | 95.8984 | 145 | 4.16 | 245 | 36.51 | 345 | 155.40 |
| −54 | 2.3694 | 4.0535 | 46 | 100.939 | 146 | 4.27 | 246 | 37.14 | 346 | 157.34 |
| −53 | 2.6917 | 4.5597 | 47 | 106.206 | 147 | 4.39 | 247 | 37.78 | 347 | 159.30 |
| −52 | 3.0542 | 5.1231 | 48 | 111.708 | 148 | 4.51 | 248 | 38.43 | 348 | 161.28 |
| −51 | 3.4618 | 5.7496 | 49 | 117.452 | 149 | 4.64 | 249 | 39.09 | 349 | 163.27 |
| −50 | 3.9193 | 6.4454 | 50 | 123.4478 | 150 | 4.76 | 250 | 39.76 | 350 | 165.29 |
| −49 | 4.4324 | 7.2174 | 51 | 129.7042 | 151 | 4.89 | 251 | 40.44 | 351 | 167.33 |
| −48 | 5.0073 | 8.0729 | 52 | 136.2304 | 152 | 5.02 | 252 | 41.12 | 352 | 169.39 |
| −47 | 5.6506 | 9.0201 | 53 | 143.0357 | 153 | 5.16 | 253 | 41.81 | 353 | 171.47 |
| −46 | 6.3699 | 10.068 | 54 | 150.1298 | 154 | 5.29 | 254 | 42.52 | 354 | 173.58 |
| −45 | 7.1732 | 11.225 | 55 | 157.5226 | 155 | 5.43 | 255 | 43.23 | 355 | 175.70 |
| −44 | 8.0695 | 12.503 | 56 | 165.2243 | 156 | 5.58 | 256 | 43.95 | 356 | 177.85 |
| −43 | 9.0685 | 13.911 | 57 | 173.2451 | 157 | 5.72 | 257 | 44.68 | 357 | 180.02 |
| −42 | 10.181 | 15.463 | 58 | 181.5959 | 158 | 5.87 | 258 | 45.42 | 358 | 182.21 |
| −41 | 11.419 | 17.170 | 59 | 190.2874 | 159 | 6.03 | 259 | 46.16 | 359 | 184.43 |
| −40 | 12.794 | 19.048 | 60 | 199.3309 | 160 | 6.18 | 260 | 46.92 | 360 | 186.66 |
| −39 | 14.321 | 21.110 | 61 | 208.7378 | 161 | 6.34 | 261 | 47.69 | 361 | 188.93 |
| −38 | 16.016 | 23.372 | 62 | 218.5198 | 162 | 6.50 | 262 | 48.46 | 362 | 191.21 |
| −37 | 17.893 | 25.853 | 63 | 228.6888 | 163 | 6.67 | 263 | 49.25 | 363 | 193.52 |
| −36 | 19.973 | 28.570 | 64 | 239.2572 | 164 | 6.84 | 264 | 50.05 | 364 | 195.86 |
| −35 | 22.273 | 31.544 | 65 | 250.2373 | 165 | 7.01 | 265 | 50.85 | 365 | 198.22 |
| −34 | 24.816 | 34.795 | 66 | 261.6421 | 166 | 7.18 | 266 | 51.67 | 366 | 200.61 |
| −33 | 27.624 | 38.347 | 67 | 273.4845 | 167 | 7.36 | 267 | 52.49 | 367 | 203.02 |
| −32 | 30.723 | 42.225 | 68 | 285.7781 | 168 | 7.55 | 268 | 53.33 | 368 | 205.47 |
| −31 | 34.140 | 46.453 | 69 | 298.5363 | 169 | 7.73 | 269 | 54.17 | 369 | 207.93 |
| −30 | 37.903 | 51.060 | 70 | 311.7731 | 170 | 7.92 | 270 | 55.03 | 370 | 210.43 |
| −29 | 42.046 | 56.077 | 71 | 325.5029 | 171 | 8.11 | 271 | 55.89 | 371 | 212.96 |
| −28 | 46.601 | 61.534 | 72 | 339.7401 | 172 | 8.31 | 272 | 56.77 | 372 | 215.53 |
| −27 | 51.607 | 67.466 | 73 | 354.4995 | 173 | 8.51 | 273 | 57.66 | 373 | 218.13 |
| −26 | 57.104 | 73.909 | 74 | 369.7963 | 174 | 8.72 | 274 | 58.56 | 374 | 220.64 |
| −25 | 63.134 | 80.902 | 75 | 385.6459 | 175 | 8.92 | 275 | 59.46 | 374.15 | 221.20 |
| −24 | 69.745 | 88.485 | 76 | 402.0641 | 176 | 9.14 | 276 | 60.38 | | |
| −23 | 76.987 | 96.701 | 77 | 419.0669 | 177 | 9.35 | 277 | 61.31 | | |
| −22 | 84.914 | 105.60 | 78 | 436.6708 | 178 | 9.57 | 278 | 62.25 | | |
| −21 | 93.584 | 115.22 | 79 | 454.8923 | 179 | 9.80 | 279 | 63.20 | | |
| −20 | 103.06 | 125.63 | 80 | 473.7485 | 180 | 10.03 | 280 | 64.17 | | |
| −19 | 113.41 | 136.88 | 81 | 493.2567 | 181 | 10.26 | 281 | 65.14 | | |
| −18 | 124.70 | 149.01 | 82 | 513.4345 | 182 | 10.50 | 282 | 66.12 | | |
| −17 | 137.02 | 162.11 | 83 | 534.3000 | 183 | 10.74 | 283 | 67.12 | | |
| −16 | 150.44 | 176.23 | 84 | 555.8714 | 184 | 10.98 | 284 | 68.13 | | |
| −15 | 165.06 | 191.44 | 85 | 578.1673 | 185 | 11.23 | 285 | 69.15 | | |
| −14 | 180.97 | 207.81 | 86 | 601.2068 | 186 | 11.49 | 286 | 70.18 | | |
| −13 | 198.27 | 225.43 | 87 | 625.0090 | 187 | 11.75 | 287 | 71.22 | | |
| −12 | 217.07 | 244.37 | 88 | 649.5936 | 188 | 12.01 | 288 | 72.27 | | |
| −11 | 237.49 | 264.72 | 89 | 674.9806 | 189 | 12.28 | 289 | 73.34 | | |
| −10 | 259.66 | 286.57 | 90 | 701.1904 | 190 | 12.55 | 290 | 74.42 | | |
| −9 | 283.69 | 310.02 | 91 | 728.2434 | 191 | 12.83 | 291 | 75.51 | | |
| −8 | 309.75 | 335.16 | 92 | 756.1608 | 192 | 13.11 | 292 | 76.61 | | |
| −7 | 337.97 | 362.10 | 93 | 784.9639 | 193 | 13.40 | 293 | 77.72 | | |
| −6 | 368.52 | 390.95 | 94 | 814.6743 | 194 | 13.69 | 294 | 78.85 | | |
| −5 | 401.58 | 421.84 | 95 | 845.3141 | 195 | 13.99 | 295 | 79.99 | | |
| −4 | 437.31 | 454.88 | 96 | 876.9057 | 196 | 14.29 | 296 | 81.14 | | |
| −3 | 475.92 | 490.19 | 97 | 909.4718 | 197 | 14.60 | 297 | 82.31 | | |
| −2 | 517.62 | 527.93 | 98 | 943.0355 | 198 | 14.91 | 298 | 83.48 | | |
| −1 | 562.62 | 568.22 | 99 | 977.6203 | 199 | 15.22 | 299 | 84.67 | | |
| 0 | 611.153 | 611.213 | 100 | 1013.25 | 200 | 15.55 | 300 | 85.88 | | |
| Temp. T in °C | P$_i$(T) over ice in Pa | P$_w$(T) over water in Pa | Temp. T in °C | P$_w$(T) over water in hPa | Temp. T in °C | P(T) in bar | Temp. T in °C | P(T) in bar | Temp. T in °C | P(T) in bar |

## Magnetic susceptibility

Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −12.97 cm$^3$/mol.
Accepted standardized value of the magnetic susceptibility of water at 20 °C (room temperature) is −0.702 cm$^3$/g.
Magnetic susceptibility of water at different temperatures :
| Isotopolog, state | Temperature in K | Magnetic susceptibiliy in cm$^3$/mol |
| H$_2$O$_{(g)}$ | >373 | −13.1 |
| H$_2$O$_{(l)}$ | 373 | −13.09 |
| H$_2$O$_{(l)}$ | 293 | −12.97 |
| H$_2$O$_{(l)}$ | 273 | −12.93 |
| H$_2$O$_{(s)}$ | 273 | −12.65 |
| H$_2$O$_{(s)}$ | 223 | −12.31 |
| DHO$_{(l)}$ | 302 | −12.97 |
| D$_2$O$_{(l)}$ | 293 | −12.76 |
| D$_2$O$_{(l)}$ | 276.8 | −12.66 |
| D$_2$O$_{(s)}$ | 276.8 | −12.54 |
| D$_2$O$_{(s)}$ | 213 | −12.41 |
* view
* Except where noted otherwise, data relate to Standard temperature and pressure.
* Reliability of data general note.