Hydraulic fracturing, or ‘fracking’, involves the extraction of natural gas from shale formations deep underground using vertical and horizontal drilling technologies and vast quantities of chemically treated water injected into the wells under high pressure. Although commercial fracking has been underway in the USA since the 1990s, the industry is in its infancy elsewhere in the world. Rapid increases in gas production in the US have spurred interest in countries as far flung as the UK, China, Poland, Argentina and South Africa, although there is much uncertainty over potential gains and the environmental costs of the new technology (Buchan, 2013; European Commission, 2012a). In the UK, there are currently no companies actively fracking but several are undertaking exploratory drilling, and many policymakers, academics, environmental activists and energy industry specialists feel that the UK could be on the edge of a ‘fracking boom’. Some see fracking as a potential energy bonanza ensuring the UK’s energy security well into the future, while others fear that it could bring significant harm to the environment and public health. In this article, we explore several dimensions of these uncertainties generally, and assess specifically some of the implications for the UK water environment. We also suggest ways in which the UK could learn from the experiences of fracking in the USA.