Methods and systems are presented for discrete sampling of groundwater. The methods and systems presented are directed toward collecting groundwater samples at one or more locations below ground surface using one or more portable, vacuum-activated sampling devices including a collection chamber, one or more check valves, and a vacuum tube within a main body for activating the check valve to admit groundwater into the collection chamber. A groundwater inlet filter can be provided upstream of the check valve for some systems. A groundwater inlet chamber having a separate vacuum tube for purging the inlet chamber may be provided for other systems.