A low-flow emitter includes a first housing and a second housing. The first housing includes a first thread portion, and a first passage defined in the first thread portion. The second housing includes a second thread portion, and a second passage defined in the second thread portion corresponding with the first thread portion in a thread connection. Part of the thread connection between the first and second housings is a loose fitting thread connection. A spiral passage is formed along the loose fitting thread connection between the first and second housings. Water flow rate is able to be controlled by a rotation of the first housing with respect to the second housing.