No, you cannot cook food using only water in an air fryer. Air fryers work by circulating hot air around the food to cook it, creating a crispy exterior similar to deep-frying but with significantly less oil. Water is not an effective medium for cooking in an air fryer because it doesn't get hot enough to generate the necessary heat for cooking or crisping the food.
Air fryers require some form of oil or fat to help facilitate the browning and crisping process. The small amount of oil used in an air fryer is usually brushed onto the food's surface or sprayed evenly to achieve the desired texture.
If you want to use water to steam or cook your food, it's better to use traditional cooking methods like boiling, steaming, or sautéing on the stovetop or using a microwave. Air fryers are specifically designed for dry cooking with hot air, and they won't be effective if you try to cook with water alone.