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Actually, water is a significant weakener of glass and contributes substantially to an increase of the rate of crack growth in conventional silica glasses.
It is commonly understood that water molecules play the fundamental role in slow crack propagation in glasses. The dissociative adsorption of water molecules on strained siloxane bridges at the crack tip is the basic ingredient of the stress-corrosion theory for sub-critical crack growth
For slow (subcritical) crack growth, the primary controlling factor when glass is exposed to a liquid is the chemical potential of the water in the liquid. There is a stress-enhanced chemical reaction between water and the Si-O bonds of the glass.