Abstract: A buffer tank and pre-wetting apparatus prevent a liquid chemical waste from crystalizing on the inside walls of a drain pipe that carries the waste to a waste tank. The pre-wetting apparatus includes a pre-wetting tank with an overflow pipe that leads to the waste tank drain pipe. A water supply is connected to fill the pre-wetting tank to the rim of the overflow pipe and then overflow to wet the inside walls of the drain pipe before waste from the buffer tank is transferred through the overflow pipe and to the drain pipe and the waste tank.