What is the moral of the faucet downward?

It shows that the real dragon emperor paid tribute to the people. References:

The Erxian Temple in Shennong Mountain, Qinyang City, Henan Province, was founded in the early years of the Tang Dynasty. According to legend, it was built by Emperor Taizong to thank Mrs. Wei, the founder of Taoist Shangqing School (commonly known as "Grandma Erxian" among the people), and ordered Weichi Gong, Minister of Qin, to supervise the construction. The archway faucets here are all downward, which shows the real respect of Li Shimin, the dragon emperor, to grandma Erxian. The faucets in the stone archway here are all downward, which is rare in the whole country.