Nature’s best example for a circular economy is the hydrologic water cycle. Adapting the continuous movement of water on, above and below the surface to the hydrogen economy we can also observe changes in the physical state of water and chemical bonding of hydrogen and oxygen – or more generally a reducing and an oxidizing agent. In the hydrogen economy, the fear of losses and the demand for leak testing processes is mainly driven by safety concerns. The generation of a potentially hazardous mixture must be avoided. In our presentation we shall provide examples for development of a tightness specification for various components, demonstrate the feasibility in a lab experiment and show implementation into an industrial leak testing process.