There was an external water leak in ITW during the last beam running time. The leak started after the shielding blocks transfer(May 22). It cause a constantly water level drop on S-tank(0.5 "/day average). Today , after the blocks are moved , the leak source has been found. Water seeped through a fitting on ITW dump circuit pressure gauge. The leak water slowly flow around the TM1 on the tank flange. most of them are dried out, but left some stain on dump module and tank flange. By closing the supply and return water valves on the ITW dump circuit, the leak is stopped now. We will fix this problem after the module is moved out and the radioactive field is low.  See attachments.