And why are we faffing about with this tiny bottle of holy water here, and that tiny bottle of holy water there? Instead: take a priest to Land's End and have him bless the Atlantic ocean. Fly him then to California and have him bless the Pacific. For completeness sake, scoot him over to India and have him bless the Indian ocean.
Then, as the natural cycle draws moisture into clouds holy water will fall from the sky. Plants will soak it up, mists and dew will be holy, and the vampires will dissolve in agony world wide. As we drink and eat, holy water will seep into our bodies and form the medium for our red cells. Drinking our blood will scald and destroy vampric mouths and gullets. Breathing the moist air will corrode their lungs. Within a year all vampires will be gone.