Natural Organic Matter Character in Drinking Water Distribution Systems: A Review of Impacts on Water Quality and Characterization Techniques

Natural Organic Matter (NOM) in water arises from decomposed plant and animal matter and is ubiquitous in drinking water sources. The variation in NOM concentrations and characteristics, influenced by events like floods and droughts, plays a crucial role in water treatment efficiency and water quality received by the public. For example, increased NOM concentrations necessitate higher levels of coagulants and disinfectants, leads to the formation of disinfection by-products (DBPs), and plays a key role in biofilm development. When considering impacts of NOM, it is not only the presence or concentration but the makeup or proportion of varying sub-groups which can impact water quality. Formation of DBPs, corrosion and scaling, pollutant transport, aesthetic deterioration, and biofilm growth are dependent on the relative composition of NOM within the distribution system. Although the role of NOM concentration and characteristics is well studied during treatment, the impacts of residual NOM in water distribution systems have received less attention. In particular, it is clear, due to the varying roles of NOM sub-groups, that greater consideration of NOM characteristics in distribution systems is needed. This paper reviews the broad implications of NOM characteristics for water distribution systems and explores challenges and opportunities in NOM characterization within distribution systems. Furthermore, the influence of NOM characteristics in premise plumbing is examined. The review highlights the necessity for precise NOM characterization and real-time monitoring, aiming to strengthen water distribution system resilience.