The paper presents an hardware solution for the realization of wireless sensors able to flow, without any anchorage, through the pipes used for fluid transportation, located on the terrain, but also under the ground surface. The designed sensors do not need any direct connection to the surface, communicate via wireless channels towards fixed stations positioned out of the ground, and provide a complete analysis of fluid pipes, in terms of survey, path identifications, damage recognition and leakage prevention. The electromagnetic components, particularly the antenna, are chosen in order to optimize the data transmission towards the surface. Antenna design and channel propagation modeling are based on a dedicated full-wave solution of the problem. To validate the introduced technological solution, an ldquoad-hocrdquo wireless sensor network has been designed and tested, thanks to the collaboration of the aqueduct company ldquoAcquedotto del Monferratordquo. In a dedicated test space, analyses were performed on water pipes of different dimensions at varying depths in the ground, up to 2.5 meters. Results show excellent performance and reliability.