<p dir="ltr">Antibiotic resistance among bacteria is a growing public health concern and can result in treatment failure and economic loss. Point-of-use (POU) water filtration systems have been often used to remove contaminants from drinking water but the potential development of antibiotic resistance in POU systems has not been fully investigated. This study investigated the development of biofouling and the emergence of antibiotic resistance in activated carbon (AC) and reverse osmosis (RO) POU filters. Both filters experienced significant biofouling during short-term and long-term testing, characterized by microbial biomass and organic matter accumulation. Microbial growth and horizontal transfer of antibiotic resistance genes were observed in both systems, which were influenced by treatment capacity and nutrient availability. Phosphorus concentration was found to play a significant role in promoting microbial growth and horizontal gene transfer. Furthermore, the study examined the impact of biofouling on filter performance and removal of emerging contaminants, such as per- and polyfluoroalkyl substances (PFAS). While PFAS were effectively removed by both AC and RO filters, long-chain PFAS removal efficiencies were affected by biofouling development, especially in the AC system. The presence of emerging contaminants may contribute to the complexity of biofouling and affect antibiotic resistance dynamics in water treatment systems. Both short-term and long-term filtration experiments showed that fouling development and microbial growth may play an important role in the development of antibiotic resistance through horizontal gene transfer. Understanding the interplay between biofouling, antibiotic resistance, and emerging contaminants is crucial for optimizing water treatment processes and mitigating public health risks. Further research is needed to develop effective strategies for controlling biofouling and preventing the spread of antibiotic resistance in water treatment systems to safeguard human health.</p>