The results of experimental and calculating-theoretical research of pulse discharge electrophysical and hydrodynamic characteristics in water with the energy in the impulse of ~ 0.5J are represented in the paper. The intensity of plasma radiation in continuous and line spectrum were measured experimentally. Structure and dynamic of plasma column were fixed by special high-speed camera VFU-1. Temperature, pressure and ionization composition were determined from the design model. Data on specific erosion value and H2O2 concentration forming as a result of the discharge are represented. Some results of the discharge action on microorganisms (E.Coli), containing in water and also preliminary data on biological activity of water appearing at discharge action are represented at the conclusion.