[wigiv]

Not entirely accurate. Certainly for metals, stone, and other hard materials the entrained abrasive is doing the cutting, but water-only waterjet cutting is used for a lot of things: foams, rubbers, plastics, fibrous materials, food, sensitive items like diapers and medical materials (because the pressurized water is inherently sterilized, and there's no blade to gum up and hold bacteria).

And what's really going to bake your noodle is there is an additive called...wait for it...SUPER-WATER that helps maintain stream coherence out of a high-pressure waterjet nozzle, allowing even more effective water-only cutting.