Abstract: An apparatus for cleaning large, flat hard surfaces such as concrete parking lots, sidewalks and plazas is provided The apparatus receives hot pressurized water and sprays the water downwardly onto the surface to be cleaned through a rotating manifold of spray nozzles. The manifold is mounted within a pushable cart or chassis, similar to a lawnmower chassis, for rotational movement in a plane parallel with the surface to be cleaned. Nozzles of the spray manifold are tilted at an angle such that water sprayed from the nozzles provides an angular momentum to the manifold. The apparatus is also provided with a mechanism for raising or lowering the height of the nozzles above the surface and for setting a minimum selected height.