Abstract: A water jet nozzle comprises an inlet pipe extending into a converging conical section of an outlet pipe, with a narrow annular opening between the inlet pipe end and the outlet pipe inner wall. The outlet pipe also has a straight section in continuation of the smaller end of the converging conical section followed by a diverging conical section and a substantially straight outlet section. Pressurized air is introduced through the annular opening to surround the central water flow, thereby reducing friction against the outlet pipe wall, the consecutive outlet pipe sections further improving the shape and reach of the ejected water jet.