This Article considers how to regulate the risk of water contamination from fracturing. The task entails a careful balance of competing considerations. The shale boom offers enormous benefits and should be encouraged. At the same time, we need regulation to ensure that it is safe, since water is a vitally important resource. In addition, the public must believe that shale drilling is safe. Otherwise, the shale revolution could be vulnerable to regulatory overkill, as media stories about flaming water faucets, brown well water, and sickly farm animals prompt widespread public apprehension about water contamination. In order to realize the potential benefits of fracturing, we need regulation that is carefully calibrated to minimize the real risks, without deterring socially valuable drilling. This challenge is all the more difficult because fracturing can potentially contaminate water in several ways. Some are well understood from decades of conventional oil and gas production and can be controlled with best practices regulations. Others are highly speculative, may or may not present real risks, and currently have no known solutions. As a result, regulatory responses should be dynamic, generating additional information about potential risks and stimulating innovations to reduce these risks.