In the past, most of the water consumed in rural areas was groundwater because groundwater is cleaner than water in rivers. Eating groundwater requires relying on water wells. The practice of "digging wells to drink" has existed since ancient times, but the distribution of groundwater underground is complex and requires the use of experience or technology to determine the condition of the "water veins".

It is relatively easy to drill a well in the plain area, as long as it is not in a very dry season, it can quickly reach the water layer. But people have still summarized some experiences to save time, effort, and efficiently obtain groundwater. Although groundwater cannot be seen, some patterns can be discovered through the characterization of surface temperature and humidity.

The temperature of shallow groundwater at 5-10 meters is relatively constant, maintaining around 15 ℃ throughout the year, which is warm in winter and cool in summer. Based on this characteristic, we will find that in winter, in areas with shallow groundwater, the freezing time of permafrost will be later, and the thawing time will also be longer. In summer, the humidity will be higher in areas with shallow groundwater, and it will be thicker when foggy.

Of course, the above experience cannot guarantee the situation of groundwater, especially during drought, the above characteristics will be much weaker. Modern drilling often uses certain techniques to determine water veins. Common methods include electrical exploration, ground nuclear magnetic resonance water detector, magnetic exploration, and magnetic exploration. Through these technologies, it is possible to search for groundwater in more complex terrains such as karst areas and high-altitude mountainous regions.