Work fatigue is a common problem that we often encounter in workers at work. Work fatigue is also interpreted as a crucial problem that needs to be addressed because fatigue can cause work skills to disappear, health conditions decline which can trigger work accidents, and work productivity and presentation decreases. This research aims to determine the factors related to work fatigue of employees managing the intake of the IPA production section (water treatment installation) at Perumdam Tirta Kencana, Samarinda City. The research results show that the variables related to work fatigue are age (p-value, 0.035= p<0.05), work period (p-value, 0.012= p<0.05). Meanwhile, what is not related is workload (p-value, 0.063= p>0.05). The conclusion is that there is a relationship between age and length of service with work fatigue in employees managing the intake of the natural science production section (water treatment plant) at Perumdam Tirta Kencana, Samarinda City with significance values for Age (p-value, 0.035=p<0.05), Years of Service (p -value, 0.012=p<0.05) while Workload has no relationship with work fatigue in employees managing the intake of the IPA production section (water treatment plant) at Perumdam Tirta Kencana Samarinda City with a significance value of Workload (p-value, 0.063= p>0.05). It is recommended to Perumdam to provide more assurance to workers when carrying out work so that the safety and health of workers is better maintained, especially when workers are over the age of workers and reduce heavy work. Keywords: Work Fatigue, workers, age, length of service, workload, employees and workers must do things according to their body's capacity to avoid excessive work fatigue.