The submitted equation of state is proposed for the liquid phase of ordinary water substance for industrial calculations. The equation is valid to a temperature 350°C and a pressure 100 MPa. Sato's form of the equation of state has been used. To enlarge the range of validity of Sato's original equation new temperature functions have been developed and an additional correction function effective at high temperatures has been introduced. Special attention has been paid to the individual temperature functions of the equation to shorten computer calculation time.