The best Advanced Oxidation Process (AOP) system will attack the water sanitation process from several different angles. Make sure that any AOP system you purchase uses a residual sanitation process (i.e. copper ionization), hydroxyl radicals (i.e. titanium grid), Ultraviolet Light (bacterial reproduction prevention), and advanced filtration such as a 3 stage glass filtration system (never settle for 1-stage glass). You can expect to pay roughly $5600 or more for a high-quality system that integrates all of these technologies into one control panel.