We have studied the structure and dynamics of water in its binary mixture with two amphiphilic molecules 1,2-dimethoxy ethane (DME) and dimethyl sulfoxide (DMSO) by THz time domain spectroscopy (TTDS) (0.3-1.6 THz region). In both the cases a non-ideal behavior of the mixture is found owing to the formation of water clusters. The cooperative dynamics of water obtained from Debye relaxation of TTDS data reveals a non-monotonous behavior as a function of water concentration (X w ).