The bottled water industry is increasing efforts to replace plastic bottles with more easily recycled aluminum containers, or cans. The effort follows public anger about reports that plastic water bottles are severely polluting the world’s oceans. The French Danone company is the latest to replace some plastic water bottles with aluminum cans. Competitors like Coca-Cola, PepsiCo and Nestle have also started selling water in aluminum cans. Replacing plastic water bottles that pollute the seas with recyclable aluminum cans should be an easy way to help the environment, right? Maybe not. Aluminum cans might result in less ocean waste, but they also come with their own cost to the environment. The production of an aluminum can is estimated to release two times as much carbon dioxide into the air as a plastic bottle.