I used to refill my five gallon jug off the back of one of the trucks that come around all the time. "Reverse osmosis, UV light" I've been sick twice in the last three months. Then about a month ago, I noticed the truck water had a muddy taste and switched over to buying water at the colmado in sealed bottles~I haven't been sick since. It's a cash business and if a driver tops off the tank with tap water, he can prob clear another 500 or more pesos a day without the parent company knowing. It's a hassle to haul the water now and more expensive, but there's no way I'll buy off a truck again. I'm hoping to get one of those ceramic cones now..