Water Assessment and Treatment Evaluation Research Study Act of 2008 or the WATER Study Act of 2008 - Requires the Administrator of the Environmental Protection Agency (EPA) to study and report to Congress on the presence, sources, and effects of pharmaceuticals and personal care products in U.S. drinking water supplies and on ways to properly dispose of such products and improve water treatment. Directs the Administrator to examine wastewater effluent and run-off from agricultural operations in identifying such sources.