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Climatic, geographic and operational determinants of trihalomethanes (THMs) in drinking water systems

Lookup NU author(s): Maria Valdivia-Garcia, Professor David GrahamORCiD, Professor David WernerORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Trihalomethanes (THMs) are conditionally carcinogenic compounds formed during chlorine disinfection in water treatment processes around the world. THMs occur especially when source waters are subject to marine influences, high and-or regular precipitation, and elevated levels of organic matter. THMs formation is then rooted in geographic, operational and climatic factors, the relative importance of which can only be derived from large datasets and may change in the future. Ninety three full-scale Scottish water treatment plants (WTPs) were assessed from Jan 2011 to Jan 2013 to identify factors that promote THMs formation. Correlation analysis showed that ambient temperature was the primary THMs formation predictor in potable water (r2 = 0.66, p < 0.05) and water distribution systems (r2 = 0.43, p = 0.04), while dissolved organic carbon (r2 = 0.55, p < 0.001) and chloride (indicating marine influence; r2 = 0.41, p < 0.001) also affected THMs formation. GIS mapping of median THMs levels indicated brominated THMs were most prevalent in coastal areas and on islands. This real-world dataset confirms both geographic and climatic factors are key to THMs formation. If ambient temperatures increase, THMs control will become more challenging, substantiating concerns about the impact of global warming on water quality.

Publication metadata

Author(s): Valdivia-Garcia M, Weir P, Frogbrook Z, Graham DW, Werner D

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2016

Volume: 6

Online publication date: 20/10/2016

Acceptance date: 20/09/2016

Date deposited: 29/09/2016

ISSN (electronic): 2045-2322

Publisher: Springer Nature


DOI: 10.1038/srep35027


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Funder referenceFunder name
Scottish Water
EP/G037094/1Engineering and Physical Sciences Research Council (United Kingdom)