Guo Pu pointed out in the Book of Burial that the most important anger in Feng Shui has a principle, that is, "stop at the water boundary", that is, anger will stay when it meets water. Water is the key to producing gas, so water in Feng Shui is a symbol of retaining gas, which means that water can retain wealth, and areas with water are bound to be rich.
Water is also an important reference to distinguish Long Mai. Great dragons are transported by rivers, small dragons by big streams, big branches by small streams, and small branches by ditches and fields. In addition, the size of branches can also be distinguished from the length of water flow.