The integration of oxidation processes in drinking water treatment has been observed to enhance coagulation, flocculation, and subsequent particle removal processes, effectively addressing dissolved metals, algae cells, and their by-products. Despite extensive research on the impact of various oxidants on coagulation and flocculation, the interaction between oxidation processes and particle filtration remains underexplored. This study involved analysis of full-scale filtration performance data as well as results from pilot-scale studies. Full-scale operational data from the Putnam Water Treatment Plant (Greenwich, CT, Aquarion Water Company) spanning 2017-2023 was analyzed to assess how seasonal pre-chlorine dioxide (ClO2 ) addition influences physical and chemical treatment operations. Given the complex cause-effect relationship between ClO2 pre-oxidation and filter performance, the study also examined indirect impacts on media filter operation, considering variables such as raw water quality, chemical dosing, and pretreatment effectiveness. The full-scale data analysis highlights several challenges in correlating changes in unit filter run volume (UFRV) directly with pre-ClO2 treatment due to influential factors such as seasonal variations, coagulation effectiveness (linked to alum and caustic doses), and sedimentation effectiveness (related to floc-aid dose and indicated by filter influent turbidity). Moreover, pre-ClO2 affects natural organic matter (NOM) and manganese removal, modifying coagulant demands and pre-filter chlorine requirements. While pre-ClO2 impacts UFRV dynamics, these effects are embedded in a multifaceted framework where various other factors exert more significant influence. Nonetheless, pre-ClO2 tended to have a neutral to slightly beneficial effect on UFRV. In the first pilot study evaluating the impact of pre-oxidation with chlorine dioxide and ozone on dual media filter performance, two experimental rounds were conducted: pre-chlorine dioxide before coagulation in round one and pre-ozone before coagulation in round two. Each round included a control train without pre-oxidants. The study monitored head loss development at four depths along the dual media filter as well as water quality parameters after each treatment process during a filter run. The results indicated no significant difference in overall head loss development between filters with or without pre-ClO2 or pre-ozonation. However, pre-oxidation altered head loss distribution among different media filter layers, more notably with ozone than ClO2. The pre-oxidants potentially facilitated firmer floc formation, better retained in the media filter, possibly due to the destruction of organic coatings on particles, enhancing floc aggregation. The second pilot study assessed the impact of intermediate ozonation on dual media filter performance. Conducted with two parallel trains (one with post-clarification ozone and one control), the study monitored head loss and water quality parameters. Results showed that intermediate ozonation resulted in a lower terminal head loss development slope with the same alum dose, similar effluent quality in terms of UV254 and TOC/DOC, and higher turbidity and particle counts for particles under 3 µm in the ozonated water. The top 9.5 inches of the anthracite filter exhibited consistent head loss levels with and without ozone treatment, while the deeper anthracite and sand layers experienced slightly to significantly lower head loss when ozone was applied. These findings suggest that pre-oxidation and intermediate ozonation can influence filter performance, particularly in terms of head loss distribution and particle retention on the media surface.