We conduct a geospatial analysis detailing how carbon dioxide capture and sequestration (CCS) implementation affects the county-level balance of water supply and demand across the contiguous United States. We calculate baseline water stress indices for the year 2005, and explore CCS deployment scenarios for the year 2030 and their impacts on local water supply and demand. We use GIS mapping to identify locations where water supply will likely not constrain CCS deployment, locations where fresh water supply may constrain CCS deployment but brine extraction can overcome these constraints, and locations where limited fresh water and brine availability are likely to constrain CCS deployment. We conduct sensitivity analyses to determine bounds of uncertainty and to identify the most influential parameters. We find that CCS can strongly affect freshwater supply and demand in specific regions, but overall it has a moderate effect on water balances. The use of extracted brine to overcome local water constraints may enable the capture and sequestration of about 100 Mt CO2 annually over what would have been possible without brine extraction.