Yes, you can mix protein powder with water. This is a common way to prepare a protein shake or smoothie, as water is a convenient and easily accessible liquid to mix with protein powder.
When mixing protein powder with water, it's recommended to use a shaker bottle or blender to ensure that the powder is evenly distributed and there are no clumps. The amount of water used can be adjusted based on personal preference for thickness and the type of protein powder being used. Some people also prefer to use milk or another type of liquid, such as almond milk or fruit juice, instead of water for a different taste and added nutrients.