3-way taps are an indispensable part of complex infusion regimes. They play a special role in the application of medicines. Advanced treatment concepts include the application of highly concentrated active agents, which are administered exactly by doses. Medications such as anesthetics, cytostatic substances, antibiotics, narcoleptics and immunosuppressants can, together with the daily demands on the system, permanently damage the 3-way taps. Even lipids and alcoholic disinfection of connections can cause cracks.