Water wetting films much thicker than those expected from DLVO theory have been observed by several investigators. These findings are explained here by using (i) a concept of an excess of hydrogen bonds at the water/vapor interface and (ii) a theory of enhancement of interaction by change of interfacial excess quantities mediated by the classical long-range forces. According to this theory the density of hydrogen bonds in the outermost surface layer decreases, if a wetting film becomes thinner. This results in an additional, very strong repulsive contribution to the disjoining pressure.