Water experts Robert Glennon, author of Unquenchable, and Peter Gleick, author of Bottled and Sold and editor of the World's Water series, are featured in a new documentary, Last Call at the Oasis. The film illuminates the vital role water plays in our lives, exposes the defects in the current system, and shows communities already struggling with its ill-effects. Last Call at the Oasis is the latest documentary from Participant Media, creators of An Inconvenient Truth, Food Inc., and The Cove, and will be released in select cities May 4. Watch the trailer below.