The H+ national observation service (SNO H+) was created in 2002 with following missions: The first goal of the SNO H+ is to maintain and coordinate a network of experimental sites capable of providing data – including chronicles or data on long term experiments – for the characterisation, quantification and modelling of water, element and energy transfers in underground aquifers. The coupling between measurements, theories, and models is a fundamental goal of the SNO H+. The observatory aims to create a long-term relation between research teams interested in the theoretical, numerical or experimental aspects of transfers in heterogeneous media. The SNO H+ also has the task of establishing a partnership between fundamental research, training and operational partners. Training activities are organised on the exploitation of the resource and the prevention of environmental risks. The SNO H+ belongs to the national distributed research infrastructure OZCAR (Critical Zone Observatories: Research and Application) that include more that 60 instrumented sites dedicated to the observation and monitoring of the Critical Zone, the thin outer venner of Earth’s continents extending from the top of the vegetation canopy down to groundwater.