We have analyzed the photophysical evolution of a luminescent nucleoside analogous, which can be used as a DNA probe. In particular we have evidenced by using both static approaches and non-adiabatic dynamics the non-innocent role played by the first shell water molecules in tuning the evolution of the excited states. The ISC rate is strongly slowed by microhydration, in comparison to the isolated system. Indeed, our SH dynamic has shown that the life-time of the bright first singlet state is more than doubled when accounting for the presence of the first solvation shell. Interestingly, we have also evidenced that the water network leads to a complex succession of excited state proton transfer, ultimately inducing the tautomerization of the probe. This process which takes place in the ps regime may involve either two or one water molecules, and proceeds in the singlet manifold. In the case of the isolated probe tautomerization was also observed, yet in this case it happened through a direct intramolecular hydrogen transfer from the hydroxyl to the carbonyl oxygen. Interestingly; while in the isolated system tautomerization was increasing the ISC rate, no such correlation is observed in the case of the microhydrated probe, further confirming the role of solvent in quenching triplet population, and hence luminescence. Our study, especially thanks to the use of explicit SH dynamics, allows to describe the mechanisms of ESIPT in water media. It especially pinpoints its slowing in water environments. In particular it couples the evolution of the population of the most relevant excited states with structural effects solved at an atomistic level, the role played by the reorganization of the solvent network should be regarded as of particular importance. In this respect the present work also paves the way to the possible comprehension of the factors leading to the environmental specificity of the probe, which are essential for its functioning and, thus, should be optimized.