This work deals with the influence of the parameters of the working fluid (hydrostatic pressure, temperature, electrical conductivity) and the geometry of the electrode system (the length of the interelectrode gap and the uninsulated part of the anode) on the pre-breakdown characteristics of an electric discharge in a liquid aqueous electrolyte (breakdown voltage and breakdown delay time) and the minimum charging voltage, which provides a stable high-voltage breakdown of the interelectrode gap. Studies have shown that an increase in the hydrostatic pressure leads to an increase in most of the studied characteristics. At the same time, an increase in the specific electrical conductivity and temperature was observed to lead to their decrease. At the same time, it was suggested that the effect of temperature on the pre-breakdown characteristics is associated with a change in the specific electrical conductivity of the working fluid during its heating. The data obtained showed no effect of the length of the interelectrode gap on the breakdown voltage and its breakdown delay time, as well as the minimum charging voltage. The results of the experimental studies made it possible to develop a criterion for determining the charging voltage, which provides a stable high-voltage breakdown of the water interelectrode gap. Its experimental verification has shown that it can be applied to the design of electric discharge equipment and to the choice of technological modes of operation in the specified range of parameters.