Three groups of aerobic bacteria have shown an ability to cometabolize chlorinated solvents, especially trichloroethylene (TCE). The most widely studied are methanotrophs, which are aerobic organisms that grow on methane, and bacteria, primarily Pseudomonas species, that grow aerobically on aromatic chemicals. This study focuses on these two groups to (1) isolate appropriate organisms, (2) measure and compare degradation kinetics in batch studies, and (3) assess biotreatability in continuous-flow reactors. Treatment conditions and process limitations applicable to drinking water were emphasized. The study's results show that aerobic biodegradation of chlorinated solvents is clearly possible, yielding carbon dioxide as the main product. Practical limitations on the concentration of growth substrate that can be added in drinking water treatment will require that organisms have a relatively large rate constant to achieve significant biodegradation.