The research presented in this paper was part of an USEPA Cooperative Agreement to evaluate the performance of three types of Point-Of-Entry (POE) devices: granular activated carbon (GAC), diffused bubble aeration, and bubble plate aeration systems treating a groundwater supply containing radon. In this study, a direct comparison could be made among the individual POE systems since they were operated in a parallel flow configuration and each received the same influent raw water from an abandoned small community groundwater supply. The daily loading pattern was designed to simulate demand for a household POE system. Each of the POE systems was evaluated with respect to three primary factors: radon removal efficiency, potential operation and maintenance problems (i.e., waste disposal, radiation exposure, equipment malfunctions, intermedia pollution) and economics. The study was not intended to develop design criteria for these systems, but rather to evaluate their performance over one year of constant operation.