You like movies right? What would you think of Nintendo forming a movie production arm to handle film adaptations of their games in-house, to keep creative control over the product (which means being as faithful to the source material as possible), which would then be distributed by major studios.
"Milk is an emulsion or colloid of butterfat globules within a water-based fluid that contains dissolved carbohydrates and protein aggregates with minerals." Got that from Ullman's Encyclopedia of Industrial Chemistry.
Realistically, all liquid-based things contain water as it's the base for everything. This is mostly attributed to the fact that every living creature needs water to survive. Humans are made up of 75% water, plants need water to live and grow, etc.
That's the point I was trying to make in the thread. Even though Fire types take damage from Water type attacks, they probably use drinking water as an advantageous substance because Pokemon probably also need water to survive.