A tank insert for converting a conventional flush toilet into a flapperless, dump bucket-style toilet. The tank insert is sized and shaped to be snugly received within a water tank of the toilet, and includes a water reservoir pivotably received within a catch basin. The water reservoir is filled by the toilets water valve and the toilet's handle actuates the water reservoir to flush the toilet. Upon actuation, water within the water reservoir is discharged into the catch basin, and from there into the toilet bowl, which is effectively cleared.