A liquid treatment apparatus includes a supply chamber for receiving a fluid, a discharge chamber for discharging the fluid, and a cavitation generating chamber extending from the supply chamber to the discharge chamber. The cavitation generating chamber is operable to generate cavitation bubbles. A method of treating a liquid comprises directing a fluid from a supply chamber into a cavitation generating chamber by constricting the fluid through an orifice, wherein the orifice has a cross dimension that is substantially less than a cross dimension of the supply chamber, such that a fluid jet is formed. The method further includes allowing the fluid jet to expand downstream of the orifice such that the velocity of the fluid is reduced so that the jet axial velocity head at the chamber outlet is less than the difference between the static pressure within the discharge chamber and the vapor pressure of the fluid. The method also includes discharging the fluid into a discharge chamber via a chamber outlet.