Many Americans rely on groundwater as their source of drinking water. At the same time, significant amounts of oil and gas wastewater, including fracking waste, are injected underground for disposal. In 2012, the last year for which data are available, onshore oil and gas wells in the U.S. generated approximately 860 billion gallons of wastewater and more than 90 percent was injected underground. It is crucial that wells used for underground injection of oil and gas waste are properly designed, constructed, operated, maintained, and closed to ensure that they do not threaten underground sources of drinking water protected by federal and state statutes. This analysis of the regulation and oversight of underground injection in one state, West Virginia, found that West Virginia has failed to meet all of the state and federal standards it agreed to uphold, placing drinking water sources at risk.