A humidifier bottle attached to an in-home concentrator moistens the air. The oxygen passes through water before coming out of the concentrator and being breathed in via either a mask or nasal cannula.
The main purpose of this bottle is to maintain the humidity in the nostrils of person using.
As the oxygen coming out of the machine is dry in nature and nostrils get dry without using the humidifier. So to avoid this the oxygen is passed through the water in the bottle in the bubble form and comes out of through oxygen pipe.