For two decades it needs electricity in Indonesia is rising quickly. To cope with demand for electricity that government needs to improve supply electric. In the system of power plants that operate for long will generate loss as the heat equipment. Cooling water system is a cooling system that is used in a system of generating unit. On cooling water system often failed. Methods failure mode and effect analysis (FMEA) is a form of qualitative analysis which aims to identify the methods of failure of a cause of the failure, and the impact caused by the failure of any component and a system. Cooling water system greatly affect performance on generator on the units 1 hydroelectric power plant PB.Soedirman because it reduces the heat generated in the unit. From results of the study obtained the value of reliability of any instrumentation in cooling water system in PB.Soedirman PT.Indonesia Power reliable because the value of Risk Priority Number is less than 200.