In this work, we have found complete water miscibility for a priori, water immiscible (highly hydrophobic) ionic liquids by chemical manipulation of the quaternary ammonium cation grafted with hydroxyethyl moieties. Specifically, we were able to obtain bistriflimide-based ionic liquids completely miscible with water, even below room temperature. The underlying reason is the full integration of the OH groups of the cation in the continuous H-bonded network of water.