Natural Organic Matter (NOM) in drinking water sources originates from decomposed plant and animal matter and significantly influences water treatment efficiency and public water quality. NOM's varying concentrations and characteristics, affected by events like floods and droughts, impact disinfection by-products (DBPs), corrosion, scaling, pollutant transport, aesthetic issues, and biofilm growth. While NOM's role in treatment is well understood, its residual effects in distribution systems have been less studied. This review explores the impacts of NOM characteristics on water distribution systems, emphasizing the need for precise NOM characterization and real-time monitoring to enhance system resilience. NOM interacts with chlorine-based disinfectants, leading to DBP formation, which is influenced by NOM's composition, such as hydrophobic vs. hydrophilic fractions. High molecular weight, hydrophobic NOM increases halogenated DBPs, while hydrophilic, low molecular weight NOM reacts with bromine and iodine. NOM also affects metal leaching, bioavailability, and biofilm growth, with different sub-groups playing distinct roles. For example, nitrogen-rich NOM contributes to nitrogenous DBPs, while oxygen-rich NOM reduces their formation. These interactions complicate DBP management and highlight the need for understanding NOM's properties to mitigate health risks. Corrosion in distribution systems is influenced by NOM, with iron and copper pipes being particularly affected. NOM can promote corrosion by altering surface properties and facilitating bacterial growth, which in turn affects metal leaching and biofilm formation. The presence of NOM on pipe scales can increase metal release, especially during water stagnation. Additionally, NOM interacts with biofilms, influencing redox conditions and microbial activity, which can exacerbate corrosion. Pollutant transport is also affected by NOM, which can adsorb and transport metals, radionuclides, pathogens, and emerging contaminants. NOM's complexation with metals influences their solubility and bioavailability, impacting public health. Corrosion sediments, composed of rust and other mineral deposits, can adsorb NOM, altering their fate and transport within the system. Microbial dynamics in distribution systems are influenced by NOM, with certain organic matter fractions promoting microbial regrowth. Assimilable Organic Carbon (AOC) and Biodegradable Dissolved Organic Carbon (BDOC) are key indicators of microbial activity, with high AOC levels increasing the risk of pathogen regrowth. NOM's role in microbial regrowth underscores the importance of monitoring and managing organic matter to ensure water safety. Aesthetics of water are affected by NOM, which can cause discoloration, taste, and odour issues. Compounds like geosmin and 2-methylisoborneol, produced by bacteria, contribute to these problems. DBPs, particularly chlorinated phenolic compounds, can also influence water taste and odour, highlighting the need for effective NOM management. Premise plumbing, which distributes water within buildings, is critical for final water quality. NOM inNatural Organic Matter (NOM) in drinking water sources originates from decomposed plant and animal matter and significantly influences water treatment efficiency and public water quality. NOM's varying concentrations and characteristics, affected by events like floods and droughts, impact disinfection by-products (DBPs), corrosion, scaling, pollutant transport, aesthetic issues, and biofilm growth. While NOM's role in treatment is well understood, its residual effects in distribution systems have been less studied. This review explores the impacts of NOM characteristics on water distribution systems, emphasizing the need for precise NOM characterization and real-time monitoring to enhance system resilience. NOM interacts with chlorine-based disinfectants, leading to DBP formation, which is influenced by NOM's composition, such as hydrophobic vs. hydrophilic fractions. High molecular weight, hydrophobic NOM increases halogenated DBPs, while hydrophilic, low molecular weight NOM reacts with bromine and iodine. NOM also affects metal leaching, bioavailability, and biofilm growth, with different sub-groups playing distinct roles. For example, nitrogen-rich NOM contributes to nitrogenous DBPs, while oxygen-rich NOM reduces their formation. These interactions complicate DBP management and highlight the need for understanding NOM's properties to mitigate health risks. Corrosion in distribution systems is influenced by NOM, with iron and copper pipes being particularly affected. NOM can promote corrosion by altering surface properties and facilitating bacterial growth, which in turn affects metal leaching and biofilm formation. The presence of NOM on pipe scales can increase metal release, especially during water stagnation. Additionally, NOM interacts with biofilms, influencing redox conditions and microbial activity, which can exacerbate corrosion. Pollutant transport is also affected by NOM, which can adsorb and transport metals, radionuclides, pathogens, and emerging contaminants. NOM's complexation with metals influences their solubility and bioavailability, impacting public health. Corrosion sediments, composed of rust and other mineral deposits, can adsorb NOM, altering their fate and transport within the system. Microbial dynamics in distribution systems are influenced by NOM, with certain organic matter fractions promoting microbial regrowth. Assimilable Organic Carbon (AOC) and Biodegradable Dissolved Organic Carbon (BDOC) are key indicators of microbial activity, with high AOC levels increasing the risk of pathogen regrowth. NOM's role in microbial regrowth underscores the importance of monitoring and managing organic matter to ensure water safety. Aesthetics of water are affected by NOM, which can cause discoloration, taste, and odour issues. Compounds like geosmin and 2-methylisoborneol, produced by bacteria, contribute to these problems. DBPs, particularly chlorinated phenolic compounds, can also influence water taste and odour, highlighting the need for effective NOM management. Premise plumbing, which distributes water within buildings, is critical for final water quality. NOM in