Three years ago, a man with white hair and a ruddy grin went around one neighborhood in Jackson, Mississippi,  daring residents to drink the tap water. He’d buy you a drink, but only if you had a glass of water first. He’d buy your groceries, but first you had to take the case of bottled water out of your shopping cart. Residents of the capital city had been under a boil-water notice for weeks, and it had just been lifted: Distrust was still high, and the water was still brown. Not everyone