Abstract: The invention is a cleaning method and associated apparatus that are particularly useful for cleaning surfaces formed of relatively hard materials such as grout or industrial rolls which are contaminated with relatively hard embedded deposits of undesirable materials that are difficult to remove by conventional washing or abrading cleaning methods, and while substantially reducing the effluent resulting from the cleaning step so that the cleaning method may be conveniently used in areas where effluent disposal may be a problem such as smaller indoor rooms, areas, or equipment. The invention comprises pressurizing a cleaning liquid with a gas driven hydraulic pump and directing a flow of the cleaning liquid from a nozzle at surfaces to be cleaned at a pressure of at least about 5,000 pounds per square inch (psi) and at a volumetric flow rate of no more than about 1.