Passive diffusion samplers are used to collect water samples from groundwater aquifers for analysis of specific chemical compounds. The samplers are hung from a cable and placed in monitoring wells at the well screen for periods of at least 14 days, or until equilibrium has taken place between the water in the sampler and surrounding groundwater. They operate by diffusion of contaminants across a polyethylene membrane. No purging or disposal of purge water is necessary, which can dramatically reduce field sampling costs. The passive diffusion samplers act as a filter, so field filtering is not necessary. In fact, passive diffusion bags (PDBs) will block potassium permanganate from samples for sites using it in their remediation processes.