RPI was contracted by the Pipeline and Hazardous Materials Safety Administration (PHMSA) to update the drinking water unusually sensitive areas (DW USA) across the United States. RPI completed the original DW USAs in 2001. To identify each DW USA, candidate drinking water resources were subjected to the appropriate filter criteria (per 49 CFR Part 195.6) to identify those resources that are more susceptible to permanent or long-term environmental damage from a hazardous liquid pipeline accident. Work included collecting and preprocessing required and known optional data layers needed to run the DW USA model; subjecting the preprocessed data layers to the filter criteria in the DW USA model; and delivering standardized geospatial data layers with detailed metadata documents. Multiple improvements to the DW USA model were made, which greatly improved the spatial extent of the updated DW USAs, compared with the 2001 DW USAs. The final DW USA data and metadata documents were delivered to PHMSA and will be made available to vetted pipeline operators via online request to PHMSA through the National Pipeline Mapping System program. More information can be found on the PHMSA website (https://www.phmsa.dot.gov/).