This study evaluated the source apportionment and level of contamination with potential toxic elements (PTEs)—As, Cd, Cr, Cu, Ni, Pb and Zn—in a riparian zone of the Sava River by calculating the Enrichment Factor (EF) and the Geo-Accumulation Index (Igeo). The study analysed the non-carcinogenic and carcinogenic health risks to both adults and children in the local population. Soil and sediment samples collected during high and low water events from 12 sites along 945 km of the river were screened. Elevated soil contents of As, Cr, Cu, Ni, and Zn were observed along the middle and lower stretches from Županja (ZUP) to Belgrade (BEO), and an elevated Cu content was detected in the upper stretch Čatež (CAT), highlighting these elements as a potential risk for the human population. Elevated As, Cd Cr, Ni, and Zn levels in the sediment were also detected, with the Ni content three times higher than the Permissible Exposure Limit (PEL) values, indicating high contamination. The study established that As, Cr, and Ni primarily originate from geological sources; Cu, Pb, and Zn are predominantly from anthropogenic sources; and Cd originates from both geological and anthropogenic sources. Although the EF and Igeo varied along the entire river stretch, they were significantly higher for most elements in the lower stretch, indicating intensive anthropogenic contamination and potential health risks. The carcinogenic and non-carcinogenic risks associated with soils and sediments during high and low water events did not imply a potential risk for adults. However, As, Cd, Cr, and Pb potentially pose the greatest non-carcinogenic risk for children in both high and low water events, with ingestion as the main route of exposure. According to our findings, the elevated concentrations of As, Cd, Cr, and Pb in the Sava River basin (SRB) pose a significant potential health risk to the local population based on several factors: the high levels of these elements, their potential contamination risk as determined by the EF and Igeo, and their bioavailability and solubility. Although the cumulative Total Hazard Index (THI) and Total Carcinogenic Risk (TCR) values are low, particularly in the lower stretch of the Sava River, these elements still present a high potential health threat.
