A process for light water detritiation which includes the steps of water distillation for tritium stripping and enriching, followed by chemical conversion of tritium enriched water to elemental hydrogen, and finally by one or more thermal diffusion columns for final tritium enrichment. The combination of process steps takes advantage of water distillation large throughput capability at low tritium concentration with the simplicity of thermal diffusion for small throughput final tritium enrichment. The water distillation front-end and the thermal diffusion back end processes are compatible with any intermediate chemical conversion process such as electrolysis or water gas shift reaction to convert tritiated water to elemental hydrogen.