I'm confused - using your metaphor, are you saying that Water in Wine/Milk doesn't affect the actual Wine/Milk that it's in? As in it's basically a non-reactive ingredient in both?
It's the basis, the ground, the source of the wine or milk. the wine or milk are qualities that the water does not need to be water. What is water without the qualities of wine or milk? Water. What are the qualities of wine or milk without water? Not wine or milk.
What is the ocean, what is the wave? Can the ocean exist without the wave? Can the wave exist without the ocean? Is the ocean a quality of the wave, or is the wave a quality of the ocean? Is the ocean affected by the presence or absence of waves?
God is the basis, the ground, the source, unaffected by any external qualities.