A system for recovery of tritium in water has been proposed. The system is composed of CECE(Combined Electrolysis Chemical Exchange) and CTD(Cryogenic-walI Thermal Diffusion) columns. A design study was carried out for the two cases: the waste water processing in fusion facilities; and the tritium recovery from heavy water in a fission reactor in Japan. The size and power consumption of the system can greatly be reduced by using the CECE column than the system of WD(Water Distillation) columns. The operation and maintenance of the CTD column are quite easier than the CD(Cryogenic Distillation) column. The proposed system would be applicable for some cases such as the waste water processing in tritium facilities, where the processing flow rate is relatively small.