A water supply is adapted as a source for nebulized liquid through the agency of an adapter which couples oxygen pressure to a container for the water. A venturi within the adapter draws from the water supply and directs highly atomized water and oxygen through an outlet pipe on the adapter. The adapter is also provided with means of providing air to the outgoing stream in order to dilute the oxygen content.A depending suspended ball is disposed in the path of flow downstream of the venturi in a chamber. It traps water particles which should not pass to the patient. The water particles or drops collected in the chamber are drained into a means located at the bottom of the chamber. Means is located along and at the bottom to assist in collecting the liquid water and conducting it to the drain means. Conduit means is fluidally connected to the drain means and to the container for both carrying back the collected liquid water and for stabilizing pressure in the container by providing gas replacement for water removed from the system.