Disclosed are methods and devices for reducing the number of pathogens in a liquid. The methods or devices uses one or more of pressure, pressure drop, increased temperature, rate of temperature increase, and inert gas to kill pathogens. In one embodiment, inert gas is dissolved into a liquid at a pressure greater than ambient pressure. The pressure is later rapidly reduced, which causes inert gas to be released from the liquid. This reduces the number of pathogens in the liquid. Other method steps or processes that do not utilize inert gas are also disclosed.