Water plays an essential role as a solvent for a broad range of processes in nanometric confinement, for example conformational change of proteins or ion transport in biological channels. Modeling water at an appropriate level of description, microscopic enough to keep track of the molecular structure but coarse-grained enough to reach an affordable computational cost is an active domain of research. Here, we present a continuous model for polar fluids dependent on the density and on the polarization . We show that this analytical theory can capture certain features of water properties.  Because one important goal is to describe biological liquids, we present some ideas to extend this theory to diluted electrolytes.