There is a clear correlation between a decrease of ion radius and deviation from the Raoult's law at high molality as shown by the drop of water activity for LiCl and KF electrolytes (top and middle panel of Figure ). This is attributed to the higher solvation of water in the presence of smaller ions 55 that contributes to lower activity of water and conversely increases activity coefficient of electrolytes γ CnAm (Figures S8 to S10). Also, the effect of cation charge is cleary visible for divalent-cation electrolyte as water activity for all cases drops at low molality compared to monovalent electrolytes (bottom panel, Figure ). Finally, the Pitzer model reproduces the experimental activity coefficient of electrolytes γ CnAm except up to 10 mol/kg for LiCl, so that we can use the values of a CnAm water to predict intrusion pressure for electrolyte solutions in zeosils, knowing the intrusion pressure in pure water by using Equation .