Water

Liquid water from 0 to 100 °C at 1 atm — density, viscosity, specific heat, thermal conductivity and vapour pressure, all at the same state.

Phase	Liquid
Temperature range	0 to 100 °C
Source	Kell (1975) density on ITS-90; IAPWS 2008 viscosity; IAPWS-95 for cp, k and hfg; Antoine for vapour pressure

Properties at temperature

Temperature°C

Validated from 0 to 100 °C.

Density	998.2 kg/m³
Dynamic viscosity	1.0016 mPa·s
Specific heat	4.1844 kJ/(kg·K)
Thermal conductivity	0.5984 W/(m·K)
Vapour pressure	2.3296 kPa
Latent heat of vaporisation	2,453.5 kJ/kg
Kinematic viscosity ν = µ/ρ	1.0034 mm²/s
Prandtl number Pr = c_pµ/k	7.004

Send Water at 20 °C into a solver

Every fluid property in these opens already filled, all from the same state — so a density and a viscosity in one calculation always describe the same fluid at the same temperature.

Hydrostatic Pressure (P = ρgh)

ρ = 998.204

Learning zone

Water is the working fluid of most of this site, and the only one of its properties that behaves is specific heat. Density falls by 4 % from 0 to 100 °C, thermal conductivity climbs by 21 %, vapour pressure rises by a factor of 165, and viscosity drops by a factor of 6.4. Specific heat moves by 1 %, which is why 4.18 kJ/(kg·K) survives as a constant in the trade and why nothing else should.

Viscosity is the one that changes answers. Reynolds number scales as 1/µ, so a chilled-water line at 5 °C and a heating line at 80 °C running the same velocity in the same pipe sit at Reynolds numbers a factor of four apart. Laminar or transitional flow in cold, small-bore lines is far more common than designers expect, and a friction factor taken from a turbulent correlation is then simply wrong. The same factor works through every settling velocity, pump suction calculation and heat-transfer coefficient you will do.

The density curve has its maximum at 3.98 °C rather than at the freezing point. Below that, hydrogen bonds start assembling the open tetrahedral structure of ice and the liquid expands again. A cooling lake overturns until the whole body reaches 4 °C, after which colder water stays on top and freezes into a floating lid — lakes freeze from the top down, and the fish survive the winter.

Pinned constants for this substance

The constants library carries these at a single stated temperature, with their uncertainty and provenance. The table above is the same substance as a function.

Density of water at 20 °C

\rho_{20} = 998.207\ \text{kg/m}^{3}

Maximum density of water (4 °C)

\rho_{\max} = 999.975\ \text{kg/m}^{3}

Dynamic Viscosity of Water at 20 °C

\mu_{w} = 0.001002\ \text{Pa}{\cdot}\text{s}

Specific heat capacity of liquid water

c_{p,\mathrm{water}} = 4181.6\ \text{J/(kg}{\cdot}\text{K)}

Thermal Conductivity of Water

k_{w} = 0.598\ \text{W/(m}{\cdot}\text{K)}

Vapour Pressure of Water at 20 °C

p_{v} = 2339\ \text{Pa}

Latent heat of vaporisation of water

L_{\mathrm{v}} = 2,256,400\ \text{J/kg}