Drainage system, drainage units, and methods

A drainage method, comprising:

• providing at least one water receiving unit comprising:
• a water receptacle for receiving water from an adjoining surface of an upper stratum;
• and
• providing at least one drainage unit, comprising:
• a body;
• and
• standard pipes of different lengths for insertion between the water receiving unit and the at least one drainage unit;
• integrating the water receptacle into the upper stratum;
• and
• arranging and aligning the drainage unit at a distance, relative to its upper side, below the surface at least partially in a middle stratum, such that the water flowing out of the water receiving unit can flow into the drainage unit through a connection of the water receptacle and the body provided by the standard pipes;
• wherein:
• a length of each of the standard pipes achieves an individual height so that the connection is maintained irrespective of a change of the distance.