Coca-Cola shareholders grilled company leaders Wednesday on everything from the beverage giant’s contribution to obesity to its position on bottled water on college campuses, but it was a surprise appearance by billionaire Warren Buffett that stole the show.

Buffett, Coca-Cola’s largest shareholder at 400,000,000 shares, sat down for a far-reaching question-and-answer session with company Chief Executive Officer Muhtar Kent that kept the crowd of around 850 riveted.

“No business has failed with happy customers,” Buffett, 82, told the room, adding that he has never sold a single share of the company’s stock. “I’m the kind of guy that likes a sure thing, Muhtar.”

The annual get-together, held at the Cobb County Galleria, comes as the company’s stock has been riding high on improving global numbers and encouraging sales among its non-carbonated drinks in North America.

But the soft drink industry, which Coca-Cola leads, faces challenges with its biggest segment — carbonated drinks in the United States — as consumers, health officials and leaders such as New York City Mayor Michael Bloomberg link the drinks with the nation’s expanding waistline.

And Rebecca Neubardt, a student at Mount Holyoke College, represented environmentalists who want bottled water off college campuses and out of national parks. She accused Kent and the beverage industry of using marketing to make consumers question their consumption of tap water.

Kent acknowledged the role Coca-Cola is playing in obesity, but said the company does not carry the burden alone and wants to be part of the conversation addressing the issue.

“The solution is not banning, taxing,” he said. “The solution is working together.”

Segway inventor Dean Kamen also attended the meeting to pitch his Slingshot system that can sterilize any water source, including sewage. The product is being tested in several developing countries around the world with Coca-Cola’s help as part of its Ekocenter project.

“Clean water is vitally important to sustainable, healthy communities,” Kent said, adding that it also is critical to Coca-Cola’s bottom line.