The permeability coefficient is a very important influencing factor in many areas of civil engineering. Therefore, it is essential to proceed very carefully and diligently when determining and calculating it. In many cases, a simple estimation is not sufficient to make realistic calculations. As this work demonstrates, there are a variety of methods available for determination that can be utilized in practice. The challenge, as in other fields, lies in the associated effort, which also represents significant costs. However, to be able to plan and calculate economically, these investment costs are absolutely necessary.