Abstract: A humidifier with an integrated bacteriostat dispenser is disclosed. In one embodiment, a hand-operated bacteriostat pump is mounted on the humidifier housing and dispenses a predetermined amount of bacteriostat into the water tray of the humidifier when operated upon. In another embodiment, the bacteriostat automatically dispenses an amount of bacteriostat appropriate for the amount of water discharged from a water bottle into the water tray. In this embodiment, a chamber is defined for holding bacteriostat. A regulator keeps the amount of bacteriostat in the chamber at a predetermined level. A plunger head is partially disposed in the chamber and is connected to a surface the position of which changes with the water level in the water bottle. The position of the plunger head thus moves as the water level in the water bottle changes, displacing bacteriostat into the water tray. In another embodiment, a method for dispensing bacteriostat into a humidifier is disclosed.