Due to horses originally having the right away in traffic, vehicles have the right of way, so be mindful when crossing the streets as a pedestrian.
In your hotels and most restaurants, they have Eco Filtered water which is safe for drinking. Whenever in doubt, ask if the water is filtered, or grab a water bottle. Make sure to reuse water bottles and feel comfortable filling it up at any water station labeled with Eco Filter.
Antigua does strictly enforce open container laws, so please enjoy your drinks indoors before hitting the streets for more exploring!