SEH or HES Hydrogeological Experimental Site is now one of the three sites forming the National Network of Sites Hydrogeological (H + Observation Service of INSU). As such, the group “Hydr” provides a task observation maintaining a network of automatic stations acquisitions for continuous monitoring of meteorological parameters at the SEH and the evolution of piezometric levels in each well. After validation, the recorded data are systematically inserted into the database H +, whose structure has been developed jointly by the group “Hydr” and the team Geosciences Rennes (UMR 6118). Such long-term monitoring is essential to study and model the natural dynamics of water flow and chemical species in solution as physico-geochemical processes involved may be relatively long characteristic times. Sustainability in the medium term HEU is provided by (1) the recruitment in 2007 of a Software Engineer (ext. Noemi), responsible for the management and technical development of the experimental site, and (2) the financial support program “WATER-SOIL” CPER 2007-2013.