There are 2 ways to add water to the water tank.
1. Push down on the mist cap until you hear a click to create an opening in the lid and pour water into the water tank.
2. You can also push down on the mist cap to create an opening in the lid. Lift up on the lid from the opening to remove the lid. Remove the mist cap and carry the water tank to a sink to fill it up. Return the water tank to the humidifier base and place the mist cap and lid back on the water tank.