When you pour water on the top of the Garden Tower, a fraction of it will seep through the holes of the compost tube. Any excess water collects nutrients and eventually settles at the bottom, where it drains away from the compost and drips into the container beneath the drain. You don't actually make worm tea, the Garden Tower makes worm tea!
To be more technical, when we say "worm tea" in reference to the Garden Tower we're generally referring to "nutrient tea" which is a mixture of both compost drainage and of water leachate which has entrained minerals and nutrients from the entire soil column through regular watering from the top of the tower.  This "nutrient tea" has been analyzed following controlled use of the Garden Tower and is highly potent in nutrients and minerals required for healthy vegetable plant growth and should be returned to the top of the tower!