The standard partial molar volumes of 10 univalent and 5 divalent ions in water over the temperature range of its existence as a liquid at ambient pressure (0-100 degrees C) are fitted as the sum of their (negative) electrostrictive volumes and intrinsic volumes, including disordered water. The former are obtained from the shell-by-shell calculation of the electrostriction according to Marcus and Hefter that takes into account the mutual dependence of the relative permittivity and the electrical field strength of the water around the ion. This calculation yields also the spatial extension of the dielectrically saturated region around the ions. The average molar electrostriction of the water in the vicinity of the ions is also calculated and leads to estimated hydration numbers.