This invention sets forth a water flow restrictor for insertion into a water line connected to a water dispensing fixture. The restrictor includes an in-line restrictor body having a longitudinal flow passageway. The body also has an upstream coupling and a downstream coupling so that the body can be coupled into a water line. The body further has an upstream water receiving chamber and a downstream water passing chamber. An orifice of selectable restrictive size is located between the chambers. The orifice limits the flow of water through the passageway. The upstream water receiving chamber has an elliptically converging interior configuration approaching the orifice.