The watertightness between prefabricated elements used within the construction of shafts and tunnels is provided by elastomeric compression gaskets, which differ in geometry and dimensions depending on requirements. Practical needs have led to a series of laboratory tests to evaluate the gasket. These tests determined the load-deflection characteristics, resistance to differential pressure (watertightness) and stress relaxation. The results and their consequences for the practical examples from more than 20 years of the construction of tunnels show that watertightness of more than 100 bars can be obtained.