Hi Sherco, excuse the defensiveness here.
A double glazed unit is usually pressed in place by being clipped between an outer and inner bead. (Chamfered shape on the outside and inside of the window)
On more modern windows there is a black rubber/neoprene seal between the glass unit and the pvc. If hardwood it might just be a bead of sealant.
The point is that water from wfp is pretty low pressure (no more than the jet you might make after a a pint or two! (
)
So even if the rubber seal is perished or gone, all that will happen is that water will run down inside the plastic frame (not the glazed unit) and out the little drainage holes at the bottom onto the cill.
Now if the glazed unit has broken down then condensation will eventually get between the panes due to moisture in the air getting past the unit seals. Nothing to do with rain, wfp, pressure washing (not recommended!) at all.
If you are in warranty, d/g co's sometimes try to fob you off and not take the blame if they are not reputable.
Typically these units breakdown on opening panes and large panes where there is more expansion, contraction and jarring (closing hard) movement.
I think there is a site called window-man which explains it better.
