Actually per state law in Arizona it is illegal to refuse water to someone if they ask. Food, no, but water...
I'm fairly certain the "vigilante" groups down here in Cochise County have rescued more illegal aliens than any of these church groups. Any illegal found in need of food, water, or medical treatment gets it while we wait for the Border Patrol or Sheriff's Department to arrive.
This is insane. Strangers happen upon your property asking for water and the law mandates that you oblige? This translates to a number of things, one being that I would likely have to open my door and be accessible to them. They can kiss my boot heels and pound sand with tabasco on it.