The people who live in the northwest corner of New Mexico consider Darlene Arviso to be a living saint. "Everybody knows me around here. They'll be waving at me," she says from behind the wheel of the St. Bonaventure Indian Mission water truck. "They call me the water lady."

That's because Arviso hauls water for tribe members of the Navajo Nation, where, on average, residents use 7 gallons a day to drink, cook, bathe and clean. The average person in the U.S. uses 100 gallons a day.

Arviso drives to 250 homes a month filling their plastic barrels, buckets, jars and whatever containers the families have. When people see the giant yellow truck coming down the road, Navajo member Georgianna Johnson says it's like they've seen Santa coming down the chimney.

"You know what we do? 'The water truck's coming! Get the buckets ready!' We get all happy. Today's the day I'm going to take a bath," Johnson says.