The removal of trace chlorinated hydrocarbons from water has been performed through poly(dimethylsiloxane), which had been fabricated by addition crosslinking reaction. The membrane had a more hydrophobic characteristic than that fabricated by a condensation reaction because it has no polar groups in the polymeric chain, such as hydroxyl and chlorine groups. This study concentrated on the comparison of the permeation behaviors of homologous series of chloromethanes aqueous solutions with that of a chloroethane solution. It was suggested that when the hydrophobic characteristics of a membrane system is greater, water molecules in the membrane tend to exist in the form of clusters; thereby, the permeating size of water component increases, resulting in suppressing water permeation and increasing the enrichment factor for the organic component. The permeation behaviors at various temperatures and membrane thicknesses were indirectly interpreted in terms of the effect of concentration polarization and the effect of interactions of organic-membrane, and water-organic-absorbing membrane.