What's wrong with the sand outside the water in Feng Shui?

It is clear that one inch of sand water is sand and one inch is water. This is the palace gossip. Eight directions from the house to the outside For the palace, suppose Party A has a mound and there is a river behind it. There is a ditch on one side of Geng Gong, and there is a mound behind it. Compared with Geng Gong, the hills here are sand and the rivers are water. Party A's river is water outside the sand. On the contrary, the mound in Gengfang is sand outside the water.