no water will absolutely not "sterilize" pollen if it would the first time a rain fell on cannabis it would not have been able to reproduce. once pollen hits a pistil you get a seed. as for where they form it depends on where the pollen lands. you cold easily have had a hermie pop in random or a few. not every pollen grain is viable thats why they produce so many that and how many blow away and never see a female plant.