Humidifiers can include a liquid tank removably attachable to a base portion. The liquid tank can include an upper connector configured to engage a lower connector of the base portion when the liquid tank and the base portion are attached. The liquid tank can include a touch interface configured to receive a touch input from outside of the liquid tank and a liquid level sensor configured to output a signal representative of a level of liquid in the liquid tank. The base portion can include a controller that is in electrical communication with the liquid level sensor and the touch interface when the upper connector engages the lower connector. The controller can be configured to adjust operation of the humidifier based on signals received from the touch interface and can receive signals from the liquid level sensor representative of the amount of liquid in the liquid tank.