A system includes a gasifier configured to gasify a fuel contained within a fuel slurry in order to generate syngas and a black water. The fuel slurry includes at least the fuel and water. The system also includes a black water treatment system fluidly coupled to the gasifier. The black water treatment system is configured to treat the black water to generate a grey water. The black water treatment system includes a first flash tank configured to process the black water by reducing a pressure of the black water to generate a first discharged black water. The black water treatment system also includes a first flow path fluidly coupling a first discharged black water outlet of the first flash tank with a feedstock preparation system configured to generate the fuel slurry in order to provide at least a first portion of the first discharged black water of the first flash tank to the feedstock preparation system.