“Water Dragon” is a generic designation for various calculations of the San He school (Three Harmony school). They are calculations based on the measurement of the so called “Qi Mouth”, ie the point from which the energy comes. The source of energy is traditionally a river or any kind of watercourse. In fact "Water Dragon" literally means "Watercourse" or "Watercourse Energy". However, modernly, the qi or energy that powers a dwelling is more likely to come from a road or path to the main door.
One of the most simple and popular calculations of the Water Dragon is the Upward Water Method that uses a “double mountain” or 12 basic directions, corresponding to the 12 branches/animals of the Chinese zodiac. Each of the 12 directions is associated with a particular energy phase or palace. There are 4 palaces with positive Qi, 4 palaces with negative Qi and 4 palaces with more neutral Qi.
Legend has it that this calculation was created by the first great Feng Shui master, Yang Yung Sun who lived at the end of the Tang dynasty (900 AD). Having worked for a cruel emperor who disapproved of his actions (instead of supporting them with Feng Shui), he decided to flee the imperial court taking the main Feng Shui books from the palace library with him. Wanted to be executed, he took refuge in the province of Canton in southern China, near the current city of Hong Kong. He spent the rest of his life improving the Feng of villages near where he lived. Due to this legend, this type of Water Dragon is also called "method to help the poor", that is to say ordinary citizens less affluent than nobles and emperors. Today, many masters claim to be direct descendants of Yang Yung Sun.
The Water Dragon is used for houses and buildings but not specifically for apartments. In order to be applied, we need to be able to control and change change the exterior space around the house. If not, it becomes just another tool for diagnostic. However, it is very useful for urban planning and organizing the exterior of large complexes such as hospitals, football stadiums, etc. It is a form of "macro" Feng Shui par excellence.