The bonded silica adsorbent Bondapak-C18 was evaluated for removing organic matter from secondary sewage effluents and from solutions of pure organic compounds. The adsorbent is hydrophobic and its behavior with water samples may be erratic unless first wet with a solvent. However, water- ethanol mixtures behaved reproducibly and gave linear adsorption isotherms. Part of the effort was aimed at developing liquid-chromatographic methods of analysis for organic constituents of wastewater. For this work microparticulate adsorbents were used in combination with a Sep-Pak precolumn for rapid trace enrichment. Identification of the many chromatographic peaks was hampered by incomplete resolution. The chromatograms, however, were reproducible permitting comparisons of different effluents and tertiary treatment processes.