1.1 ,This practice provides for the collection of water samples with high, medium, or low suspended solids to determine the presence, count, polymer type, and physical characteristics of microplastic particles and fibers. This collection practice has been validated for the collection of samples from drinking water, surface waters, wastewater influent and effluent (secondary and tertiary), and marine waters. This practice is not limited to these particular water matrices, however, the applicability of this practice to other aqueous matrices must be demonstrated.