Bimolecular condensates are cellular compartments, whose formation occurs via liquid-liquid phase separation of proteins. The impact of protein sequence and solvent conditions on the hydration environment in bimolecular is investigated here with THz-FTIR spectroscopy. Distinct changes in the condensate hydration are only observed for a change in solvent conditions, revealing that the formation of biomolecular condensates is regulated through protein-solvent interactions rather than protein-protein interactions.