[en] In a recent H₂O-D₂O molar volume isotope effect study on the alkali metal halide solutions, individual ionic standard partial molar volume contributions (V-bar_ion⁰(H₂O)-V-bar_ion⁰(D₂O)=ΔV-bar_ion^0(H-D)) have been derived, dependent only on the chosen (Pauling) ionic radii, r_ion. It has been concluded that the isotope effect of the cations (except for Li⁺) and that of the chloride anion exhibit a linear function of 1/r_ion, with ΔV-bar_ion^0(H-D) vanishing when 1/r_ion approaches zero. On the other hand, the directly measurable hydrodynamic 'cosphere' volumes of the ions, V-bar_cosph⁰, derived from the kinetic ionic (Stokes) radii, show a similar pattern, here also the cationic and anionic r_ion relations cross or meet at V-bar_cosph⁰(Cs⁺)≅V-bar_cosph⁰(Cl^-). Because both ΔV-bar_ion^0(H-D)andV-bar_cosph⁰ originate in the hydration volumes of the ions, (V-bar_hydr⁰=V-bar_ion⁰-V-bar_intr⁰) determined by electrostriction, this r_ion pattern of the V-bar_hydr⁰ (ion) provides an 'extra-thermodynamic' assumption to evaluate the individual cationic and anionic molar volume contributions in normal water solution. As a basis for the evaluation, this r_ion pattern is applied to the conventional cationic and anionic V-bar_hydr⁰ (ion) values (related toV-bar_ion⁰(H⁺,aq.)=0cm³.mol^-1), calculated from literature V-bar_ion⁰ data, assuming that the V-bar_intr⁰ (ion) = V-bar_cryst⁰ (ion). To adjust the V-bar_hydr⁰(Cl^-) to the V-bar_hydr⁰(Na⁺,K⁺,Rb⁺,Cs⁺)versus r_ion relation at T = 298.15 K, the conventional anionic V-bar_hydr⁰ (ion) data have to be increased, the cations have to be decreased by 4.2 cm³ . mol^-1. Similar adjustments at five different temperatures between T = (273 and 323) K, result in V-bar_ion⁰(H⁺,aq.)=-(4.2±0.2)cm³.mol^-1 at T = 298.15 K, with an increment of -0.02 cm³ . K^-1 . mol^-1. Related to these parameters, relations of V-bar_ion⁰versus temperature for the alkali metal and halide ions were calculated. The cationic and anionic V-bar_hydr⁰ (ion) values, when related to V-bar_ion⁰(H⁺,aq.)=-4.2cm³.mol^-1, show strong r_ion correlation with V-bar_cosph⁰, their ratio versus r_ion offers a linear equation to compare the influence of the ions on the solvent structure on a well defined 'quantitative' scale. The value of the derived V-bar_ion⁰(H⁺,aq.), while being consistent with that widely accepted ca. - (5 ± 2) cm³ . mol^-1, has a higher precision with a reasonable basis of the applied 'extra-thermodynamic' assumption. It can serve to verify other partitioning procedures used in non-aqueous solvents