Water diffusion into silica glass results in a thin zone near the surface of the glass. In this zone the water reacts with the SiO₂ structure and "damages" the originally intact SiO₂ rings. The consequence is a reduced Young’s module. This effect can be described by use of continuum damage mechanics according to Kachanov and Lemaitre. In this report the dependency between hydroxyl concentration and damage will be described for large water concentrations by using the Wang-model. In addition the implications on strength of pre-damaged materials, deformation behavior and crack-tip stress intensity factor are addressed.