Groundwater samples from public and private drinking water wells throughout the state of New Hampshire were analyzed for total Arsenic (As). Samples were collected after pH, specific conductivity, dissolved oxygen, and water temperature had met stabilization criteria as outlined in the USGS National Field Manual (United States Geological Survey 2005).The As analyses were carried out in the geochemistry laboratory in the Department of Earth Sciences at the University of New Hampshire (UNH). Not including replicate analysis, a total of 527 samples were analyzed via a hydride generator-inductively coupled plasma mass spectrometer (HG-ICP-MS) using a Cetac HGX-200 plumbed into a Nu Instruments Attom high-resolution inductively coupled plasma mass spectrometer following procedures adapted from Klaue and Blum (1999). Diluted aliquots of sample were run in triplicate, and the reported uncertainty is the standard deviation on the mean of these analyses. Generally, the data have a detection limit of ~ 0.2 μg/L as determined from repeated assessment of analytical blanks and using the conventional approach of defining the detection limit as the mean blank + ten times the standard deviation around the mean blank. These data are sensitive as they include sampling locations from privately owned wells, hence, latitude and longitude information is not included with the data set.