As August 10, 2007, Water Conditioning plant had regenerated for DI plant, but it could not finish the process. We found that in the anion tank had mixed with cation resin. It is happened by filter nozzles under the cation tank were broke. We opened the tank’s lids and took all the left cation resin out, changed filter nozzles under cation tank. After that, brought cation resin back to an anion tank and closed the lids. Then back wash and regenerate the water again and submit to DI plant. However, the operation cycle of cation tank is shorter from 2,000 m3 to 400 m3. Its result of the quantity of cation resin in the cation tank is too little as its loss from transferred.