To evaluate the removal efficacy of an integrated membrane treatment pilot plant, methods modified from the milk and pharmaceutical industries were used to grow and concentrate B. subtilis for spiking studies. Concentrations of naturally occurring aerobic sporulating bacteria in the Hillsborough River vary significantly. Samples were heat shocked and assayed for bacteria using filtration onto nutrient agar with trypan blue. Monitoring of the existing full scale treatment facility demonstrated that endemic levels could only demonstrate at best a 2 to 3 log removal. Proposed regulations suggest that protozoan removal requirements may be as high as 6 log removal. By using controlled spiking experiments, pilot plant treatment options can be evaluated for their ability to remove protozoan sized organisms. Includes 3 references.