Thermal Conductivity of Water
| Value | 0.598 W/(m·K) |
| Status | Measured: ± 0.003 W/(m·K) (0.005 relative) |
| Source | IAPWS / CRC Handbook of Chemistry and Physics, 104th ed. |
| Categories | Material PropertiesEngineering & Trade |
| milliwatt per meter-kelvin | 598 mW/(m·K) |
| BTU inch per hour square foot Fahrenheit | 4.1462161 BTU·in/(h·ft²·°F) |
| watt per meter-kelvin | 0.598 W/(m·K) |
| watt per meter-Celsius | 0.598 W/(m·°C) |
| kilocalorie per hour meter Celsius | 0.51453155 kcal/(h·m·°C) |
| BTU per hour-foot-Fahrenheit | 0.34551801 BTU/(h·ft·°F) |
| watt per centimeter-kelvin | 0.00598 W/(cm·K) |
| calorie per second centimeter Celsius | 0.0014292543 cal/(s·cm·°C) |
| kilowatt per meter-kelvin | 0.000598 kW/(m·K) |
Water at any temperature
0 to 100 °CThe value above is one point on this curve. Liquid water from 0 to 100 °C at 1 atm — density, viscosity, specific heat, thermal conductivity and vapour pressure, all at the same state.
Learning zone
Water conducts heat better than most liquids — roughly four times better than mineral oil and 25 times better than air — thanks to hydrogen bonding, and unusually it improves as it warms, peaking near 0.68 W/(m·K) at about 130 °C before declining. It is one of the terms in the Prandtl number and therefore in every convective correlation for water-side film coefficients.
The distinction that trips people up is conduction versus convection. Still water is a mediocre insulator, but water moving through a tube transfers heat by convection at film coefficients of thousands of W/(m²·K) — the conductivity only enters through the correlation. Adding glycol makes this worse twice over: a 50 % propylene-glycol mix has conductivity near 0.40 W/(m·K) and roughly triple the viscosity at low temperature, which is why glycol loops need larger pumps and more heat-transfer surface for the same duty.