Is it possible to have a window above the shower at approximately the same dimension as the shower hob and have sufficient standard waterproof. My designer is saying there will be a big possibility of leaking / mold etc.

He is suggesting the window being 500mm above the shower, but lowest 150mm (waterproofing
standards). I have seen other houses with the windows at hob level, so how are they able to get away with it if waterproofing has to be at 150mm above?