Because of this question, we went for an experiment. Because it was not clear to us how you can drink without swallowing. The friend almost suffocated. Thanks. Don't repeat our experiment.
It's all about the structure of the pharynx and the mechanism of swallowing. When fluid from the mouth moves into the pharynx without swallowing, then the epiglottis appears on its way, which prevents it from moving into the larynx and esophagus. Therefore, the liquid accumulates in the pharynx in a kind of pocket. If the amount of contents exceeds the maximum permissible level (at which the liquid begins to overflow and enter the larynx), then the act of swallowing is performed automatically. When swallowing, the epiglottis descends, blocks the entrance to the larynx and food / liquid enters the esophagus without hindrance.
These pictures show this clearly:
But what happens to the epiglottis during swallowing (picture on the right):