What are the external water and internal water in the geomantic omen of Yin House?

What are the external water and internal water in the geomantic omen of Yin House? The answer is: Generally speaking, it is the water naturally formed in the Dragon and Tiger Sand, which is called internal water, also called internal pond water or internal ocean water, and the water outside the Dragon and Tiger Sand is external water, also called external ocean water. Under special circumstances, the water that can be seen in the field of vision is internal water, and the water outside the field of vision can be perceived as external water by impression.