A model was developed to estimate the cost of removing relatively hydrophobic VOCs from water with a pervaporation-based separation process. Evaluation of the economic model showed that the choice of a feed-side spacer in a spiral wound module has a strong effect on the total separation cost. Several spacers that yield relatively low cost separations have been identified. The choice of permeate spacer was found to have only a small effect on the process economics, though all the permeate spacers evaluated were relatively thick and open. The most economical operation is predicted to occur with moderate permeate pressures (10-12 mmHg) and membranes similar to 2 mu m thick. The specific VOC to be removed from the feed water has a significant effect on the process economics. For VOCs with relatively high Henry’s law constants, the model shows that the development of lower cost membranes with performance qualities similar to silicone rubber will be the most effective means of reducing the separation costs of this process.