The inconsistency of non-filterable solids data resulting from automatic sampling equipment used by the Surveillance and Analysis Division, Region VII, United States Environmental Protection Agency, was evaluated from a field sampling technique viewpoint. Resins and other solids of varying specific gravity and particle size were tagged with a metal salt or fluorescent material and added to a waste stream as a synthetic suspended solid to determine the collection efficiency of the samplers. Recovery of the metal salt or fluorescence was used as the indicator of solids recovery. A 832,000 liters per day (220,000 gallon per day) raw domestic wastewater flow was used to conduct the test. Recovery of solids in the hydraulic jump below the Parshall flume, and at the 0.6 depth in the approach channel above the flume was 25 percent below the theoretical homogeneous concentration indicated by the resin feed rate. The results indicate the need for a method of evaluating the wastewater characteristics for proper sample intake tube placement.