Antibiotic resistance genes (ARGs) in drinking water systems pose a critical public health risk. This study integrated metagenomic sequencing with flow cytometry to quantify the absolute abundance, diversity, mobility potential, and putative hosts of ARGs in two full-scale drinking water treatment plants (DWTPs; conventional and advanced processes) and their distribution systems over one year. The absolute abundance (copies/mL) of ARGs was calculated by multiplying cell-normalized ARG copies derived from metagenomic profiling by total bacterial cell counts measured via flow cytometry. We identified 473 ARG subtypes spanning 19 types, with total absolute abundances ranging from 1.26 × 10¹ to 1.94 × 10⁵ copies/mL. Both the conventional and advanced DWTPs could effectively remove ARGs, while substantially reshaping ARG composition and co-occurrence patterns from source water to chlorinated water. ARGs located on plasmids and co-occurring with mobile genetic elements indicated potential gene transfer capability. Metagenomic assembly and binning assigned ARGs to 78 bacterial genera, revealing marked shifts in host composition along the source-to-tap continuum. Notably, multi-antibiotic-resistant and potentially pathogenic genera, including Enterobacter, Pseudomonas, Acinetobacter, Burkholderia, and Mycobacterium, were detected in chlorinated and tap water. These results provide quantitative, system-scale insight into ARG fate and potential exposure risks in drinking water, informing risk-based management and surveillance strategies.