Water cooling system (1) for a plasma gun (2), method for cooling a plasma gun (2) and method for increasing a service life of a plasma gun (2). The system (1) includes a water cooler structured and arranged to remove heat from cooling water to be supplied to the plasma gun (2), a controller (7) structured and arranged to monitor a gun voltage of the plasma gun (2), and at least one flow valve (8) coupled to and under control of the controller (7) to adjust a flow of the cooling water. When the gun voltage drops below a predetermined value, the controller (7) controls the at least one flow valve (8) to increase the plasma gun temperature and the gun voltage.