The U.S. Environmental Protection Agency-Drinking Water Research Division uses a three tiered approach to research. The first step is bench-scale, where the chemical behavior of the organic contaminant can be investigated in a closely controlled environment. The next level, pilot-scale, is an attempt to match the contaminant with an existing water treatment process. The final step is to take the most promising treatment ideas to the field for full-scale evaluation (to examine operational problems and costs) at one or more sites with waters having the organic contaminant(s) of concern. This sequential approach to treatment research is being used on EPA-DWRD's three highest priority organic issues: volatile organic compounds, synthetic organic compounds, and disinfection by-products.