Ultrasonic water treatment is based on the ability of an ultrasonic device to induce cavitation in the liquid, generating physical and chemical effects that can be exploited to produce effective treatment. This requires that the device be both capable of generating high amplitude pressure waves in the treatment volume and capable of treating a large volume of fluid by having a large radiating surface. Most conventional ultrasonic radiators fulfill only the first of these two objectives, rendering such devices highly unsuitable for use in high-volume, high-flow liquid processes.