What Comes After LaCroix? Bevi!

Sean Grundy, Bevi’s co-founder and C.E.O., who is thirty-four, wandered into the party, wearing a blue-and-white gingham shirt. He grabbed a compostable plastic cup with the beginnings of a soda-water mojito. Grundy and his fellow co-founders, Eliza Becton and Frank Lee, teamed up in 2013, while Grundy was studying at the M.I.T. Sloan School of Management. He had just quit his job at an environmental-conservation group, and Becton, a mechanical engineer turned designer, was passionate about replacing disposable water bottles. The trio created a Bevi prototype and parked it at a gym in Somerville, Massachusetts.