We have developed a novel advanced enrichment apparatus for environmental tritium analysis called SPET (Solid Polymer Electrolysis for Tritium Water). It generates no explosive gas, requires no aqueous electrolyte, terminates enrichment rapidly, and the volume reduction is infinite. It has an automatic shutdown system which gives uniform conditions on every run, making the handling and determination of tritium concentrations very easy. The reliability of SPET was studied using environmental concentration standard water and the reproducibility error was found to be within 4%, which is sufficient for environmental measurements.