The Snap Sampler is a patented (US Pat. 7,178,415) groundwater sampling device that employs a unique double-end-opening bottle with “Snap” sealing end caps. This dedicated, in-well equipment is deployed at the desired position in the screen interval with up to six Snap Samplers and six individual sampling bottles. The design allows for the collection of groundwater samples which are in dynamic equilibrium with the aquifer through a simple, no purge/passive technique. To operate, Snap Samplers are loaded with Snap Sampler bottles and the "Snap" caps are set into an open position. Samplers are deployed downhole with an attachment/trigger line and left to equilibrate downhole for days, weeks, months—even possibly a year or more. Depth is not known to be limited, with current maximum depths of collection in excess of 2000 feet/600 meters. To collect samples, the Snap Sampler bottles seal under the water surface by simply pulling the mechanical trigger line, pushing the electric trigger button, or pressuring up the pneumatic trigger system. The trigger releases PFA (Teflon) "Snap Caps" that seal the double-ended bottles. The end caps are specially designed to seal the water sample within the bottles with no headspace vapor. Once the closed vial is retrieved from the well, the bottles are prepared with standard septa screw caps and labeled for laboratory submittal. Bottles are available in glass 40ml VOA vial size or plastic 125ml and 350ml sizes. The 40ml VOA vial can be used directly in standard laboratory autosampler equipment. With Snap Sampler VOA vials, the groundwater sample is never exposed to the open air from the point of collection downhole to the gas chromatograph. The 125ml or 350ml POLY bottle also seals in situ. The plastic bottle can be used for larger volume collection and for metals or other analytes where a plastic bottle is preferred. For non-volatiles, this bottle can be opened at the well head to combine in a larger bottle, transfer to a glass bottle (e.g. for SVOCs), or just to remove the internal spring before acidifying a metal sample. Snap Samplers with 40ml and 125ml bottles fit in 2-inch or larger monitoring wells. Snap Samplers with 350ml bottles fit in 4-inch or larger monitoring wells.