Clear vomit normally indicates there is absolutely nothing left in your stomach to be vomited up apart from stomach secretions. When you throw up, your body violently acquires the stomach to send its components upward and also out of your mouth. Your vomit may be clear if you consumed alcohol a great deal of water lately also. Fast overconsumption of water can also cause throwing up, as your stomach becomes overdistended and also forces you to throw up. Vomit is generally clear when you have not eaten in awhile, you have actually ingested a lot of water, or you have actually previously vomited all previous food from your belly.

Source