There is disclosed a system capable of purifying water to a laboratory grade level that uses redox media, high energy catalytic activated carbon, ultraviolet radiation and high purity ion exchange media in series filtration. The system produces purified water having a specific resistance of at least 18.2 megohm·cm at 25° C. with low organic carbon content. The system is designed to be fabricated on a sufficiently small scale to fit on a lab bench top.