The Alameda County Water District (ACWD) operates two surface water treatment plants that treat water from the same source. Both plants use conventional treatment, and both recycle water that has been used for filter backwashing. However, the two plants use very different technologies for treating the recycled water. This study compares the performance of the two recycled water treatment methods in terms of their ability to remove aerobic bacterial spores (ABS). The objectives of this study were to assess the fate of spore-forming pathogens (such as Giardia and Cryptosporidium) through the washwater treatment system, and determine the impact of washwater recycling on the ability of a plant to remove these pathogens. Each sample collected was analyzed for ABS, turbidity, and particle counts. In addition, chlorine residual readings were collected where appropriate (from sample locations downstream of chlorine addition). Samples for ABS were analyzed. Turbidity samples were analyzed using a Hach 2100AN analyzer. Particle counts were done with a MetOne WGS267 analyzer, and are reported as the total number of particles counted greater than the detection limit of the sensor (2 microns). Chlorine residuals were determined by amperometric titration using a Fisher & Porter analyzer.