This work comparatively investigated the formation of ketoacids of a filtered river water in synthetic goethite-catalyzed ozonation and ozonation alone. Results indicate that the catalytic ozonation produces less pyruvic acids and total ketoacids than ozonation alone. In addition, the yields of total ketoacids of the filtered water after catalytic ozonation increased as ozone dose increased and contact time extended. In comparison to ozonation alone, FeOOH/O3 further enhanced the degree of oxidation of the macromolecular intermediates or by-products such as pyruvic acid due to more •OH generation. However, Bio-filtration is still proposed to follow the catalytic ozonation to ensure the microbial stability in water distribution systems.