The kidney is the first target organ of heavy metal toxicity due to its capacity to reabsorb and accumulate divalent metals. Hemodialysis therapy is used to purify the blood of individuals with impaired kidney function. This study aimed to evaluate the quality of treated water used in the hemodialysis unit at Nalut Central Hospital, Nalut, Libya, by determining the concentrations of selected heavy metals and comparing them with international standards. A descriptive analytical approach was adopted. Water samples were collected post-treatment from the reverse osmosis system using sterile containers under strict hygienic conditions. Laboratory analyses were conducted using an atomic absorption spectrophotometer to measure the concentrations of zinc, cadmium, chromium, lead, copper, and aluminum. The results revealed critical variations; elements such as zinc (0.93 mg/L), cadmium (0.16 mg/L), and copper (0.57 mg/L) significantly exceeded the permissible limits set by AAMI standards. Conversely, chromium (0.002 mg/L) was within acceptable parameters, and both lead and aluminum were not detected. This study concludes that the treated water does not fully comply with international safety standards, indicating a partial inefficiency in the current water treatment system. It is highly recommended to enforce rigorous maintenance procedures for the reverse osmosis system and implement routine monitoring protocols to mitigate health risks associated with heavy metal accumulation in hemodialysis patients.