They stand out in the forest or field: gray metal pipes sticking out of the ground. They fulfill an important function.
Maybe some people have already noticed them while walking in the woods – the gray tubes that stick out of the ground in the forest and in the field. But what are they actually used for?
Officially, the tubes are called groundwater measuring points and are embedded between six and twelve meters deep in the earth. They are used to collect groundwater data. More precisely, the groundwater level and groundwater quality – such as chemical contamination – are measured.
Measuring points also in the city
Each of these measuring points is equipped with a special well cap that is closed and can only be opened with a specific tool. This is to prevent vandalism and tampering. The state offices for the environment and consumer protection are responsible for the measurements.
These measuring points are also everywhere in cities. However, the tubes do not rise up there, but can be found below the street. They have round or oval metal lids, which are often marked with the inscription “Groundwater measuring point” or the abbreviation “GWM”.
EU-wide Water Framework Directive
In order to take a water sample for measurement, a so-called cable light plumb bob is lowered into the tube. There is an electrode attached to the tip of the cable that uses electricity to read how high the groundwater level is.
This constant measurement of groundwater is part of an EU directive that is intended to improve the status of water bodies in all member states. According to the Federal Environment Agency, in 2022 there were a total of 7,715 measuring points nationwide for monitoring the quantitative status and 7,869 measuring points for monitoring the chemical status of groundwater.
