Abstract: TThe present invention provides a water reservoir for humidification of the gas delivered by a gas-delivery device. The water reservoir comprises of a container having at least one opening for gas movement, and a means to prevent water escape through the aperture while allowing passage of gas to be humidified and delivered to a subject. Preferably the means to prevent water escape is a baffle. Preferably the baffle is disposed opposite at least a portion of the opening. The baffle may be continuous with a wall of the container. The container may be comprised of a deformable material.