The sensitivity of electronic properties of organic conductors to minute modifications of their solid-state structure is investigated here within BEDT-TTF (ET) salts with organic bis-sulfonate anions, where specific hydrogen bonds between water molecules and sulfonate moieties are shown to dynamically control the organic slabs' electronic structure. While the mixed-valence, 2,6-naphthalene-bis(sulfonate) salt, (ET)4(NBS)*4H2O, exhibits a charge order state already at room temperature, the corresponding salt with the 2,6-anthracene-bis(sulfonate) dianion, formulated as (ET)4(ABS)*4H2O, is metallic at RT and exhibits a metal-insulator transition at TMI = 85 K. The origin of the MI transition is revealed from a combination of temperature-dependent spectroscopic (Raman) measurements, X-ray structure elucidations (from 300 to 15 K), and theoretical investigations, demonstrating that the charge disproportionation observed below TMI is associated here with the progressive switching of bifurcated OH***O hydrogen bonds between the sulfonate moieties of the anion and the trapped water molecules. These movements within the anion layer are transmitted through weaker C-H***O interactions to the two A and B donor molecules, modifying the details of the overlap interactions within AA and BB pairs and opening a gap in the band structure.