A trash tank includes a tank body which has a top open end and a partition which divides the tank body into an upper section and a lower section. The upper section receives a trash bag with a mouth disposed on a periphery of the top open end of the tank body. An elongated pedal member has a first end pivoted to an internal wall of the lower section of the tank body and a second end extending out of the tank body. A clamping device is provided for clamping detachably the mouth of the trash bag. The clamping device is disposed on the top open end of the tank body. An actuating device is provided for actuating the clamping device by means of pedaling the elongated pedal member. A fastening device is provided for fastening the mouth of the trash bag after the clamping device is detached from the mouth of the trash bag.