The reason for this is the following：
1. At present, civil engineering is very popular, because China is in the wave of urbanization and needs large-scale construction. But in another 20 years, once urban houses are saturated and the number of projects is greatly reduced, it means that a large number of civil workers are in danger of unemployment. From the development course of developed countries such as Europe, America and Japan, it can be clearly seen that it is inevitable that civil engineering will move from a popular specialty to an unpopular specialty in the future.
2. At present, water supply and drainage works are mainly in the auxiliary position of civil engineering. The prosperity of civil engineering can promote the prosperity of water supply and drainage engineering, but the decline of civil engineering will not affect the development of water supply and drainage engineering. Because water supply and drainage engineering is an interdisciplinary subject of civil engineering and environmental engineering, it will have a bright development prospect in the future when human beings pay more attention to environmental protection and the "water crisis" is getting worse.