About the last thing Selena James wants to do is drink water from a can.

“Something like that would scare me,” Ms. James, 53, said after buying a bottle of Mountain Dew at a corner deli in Brooklyn. “You see juice in a can, not water. You see water in a bottle.”

Her instinctual aversion to water in a can highlights a challenge facing one of the world’s biggest beverage companies, PepsiCo, as it seeks to persuade consumers to embrace a new product it says is meant to help the environment.

Pepsi said Thursday that starting early next year, its Aquafina brand of water would be test-marketed in aluminum cans at some retailers and food-service providers.

Stacy Taffet, the Pepsi vice president who oversees the company’s water brands, acknowledged that while many kinds of fizzy water already came in aluminum containers, drinking still water from a can would be “a newer behavior” for many people.