Potable groundwater resources could be affected by salinization as result of subsurface utilization like CO2 injection. We examine the potential of freshwater impairment for shallow aquifers and a drinking water well due to upward displacement of saline formation water along an erosional channel and a fault for a prospective storage site in the Northeast German Basin. Location and degree of salinization is governed by the hydrogeological properties of the migration pathways, while the initial local groundwater flow has only a minor impact. Moreover, an early warning is possible within the time frame of a few months.