Water Properties Chart: Density, Viscosity, Cp, 0-100 C

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Water Properties Chart: Density, Viscosity, Cp, 0-100 C

Reviewed by MLC Editorial Team | 4 August 2026

Verified by Rachel Mayfield, Supply Chain Analyst - August 2026

Properties of water from 0 to 100 degrees C at atmospheric pressure: density, dynamic viscosity, specific heat capacity and saturation vapour pressure. These are the four values that pump sizing, heat transfer and NPSH calculations keep reaching for. Values are standard steam-table figures; for precision work use the IAPWS formulation directly.

Water properties, 0-100 C

Temperature	Density (kg/m3)	Dynamic viscosity (mPa s)	Specific heat (kJ/kg K)	Vapour pressure (kPa)
0 C	999.8	1.792	4.217	0.611
10 C	999.7	1.307	4.191	1.228
20 C	998.2	1.002	4.182	2.339
30 C	995.7	0.798	4.178	4.246
40 C	992.2	0.653	4.179	7.384
50 C	988.0	0.547	4.181	12.35
60 C	983.2	0.467	4.185	19.94
70 C	977.8	0.404	4.190	31.19
80 C	971.8	0.355	4.197	47.39
90 C	965.3	0.315	4.205	70.14
100 C	958.4	0.282	4.216	101.33

What the trends mean in practice

Density falls only 4% from 4 C to 100 C, so mass-flow arithmetic barely notices temperature. Viscosity is the opposite: it drops more than six-fold from 0 C to 100 C, which is why cold-water pressure drop calculations can be badly wrong if run with the textbook 20 C value. Vapour pressure climbs steeply above 60 C - the direct cause of cavitation in hot-water pump suction lines: at 90 C water boils at just 30 kPa of vacuum.

Pump work: where these numbers plug in

Hydraulic power is flow x head x density x g - use the density row for your operating temperature. NPSH available subtracts the vapour pressure row from suction pressure, which is why the same suction layout that works cold can cavitate hot. Our pump power calculator takes these values directly.

References

IAPWS-consistent steam table values

Frequently Asked Questions

What is the density of water?

998.2 kg/m3 at 20 C, falling to 958.4 kg/m3 at 100 C. Water's maximum density (1,000.0 kg/m3) is at 4 C. For most engineering arithmetic 1,000 kg/m3 is close enough; for hot systems use the temperature-matched value.

What is the viscosity of water at 20 C?

1.002 mPa s (equivalently 1.002 cP) dynamic viscosity at 20 C. It falls steeply with temperature: 1.792 at 0 C, 0.653 at 40 C, and 0.282 mPa s at 100 C - a bigger swing than most pressure-drop calculations assume.

Why does hot water cause pump cavitation?

Because vapour pressure rises steeply with temperature: 2.3 kPa at 20 C but 70 kPa at 90 C. Hot water flashes to vapour at pressures that cold water tolerates easily, so a suction line that works cold can cavitate hot. NPSH calculations subtract vapour pressure directly.

References

IAPWS-consistent steam table values

Independent UK engineering trade publication. Company profiles cross-referenced with Companies House.