Climate change–driven alterations in water quality and their impact on trihalomethane formation: A review of treatment technologies

Climate change increasingly compromises drinking water quality by altering source water conditions. Beyond gradual warming and shifting precipitation, extreme events such as droughts, floods, and wildfire runoff rapidly change raw water composition, raising natural organic matter (NOM) and turbidity. These shifts challenge drinking water treatment plants (DWTP) by increasing disinfection by-product formation, particularly trihalomethanes (THM), during chlorination. Overall, climate change is shown to increase turbidity, nutrient loads, and NOM concentrations in source waters, with NOM exerting the strongest influence on THM formation potential. Elevated temperatures further accelerate reaction kinetics, compounding public health risks. This review analyses scientific literature on THM formation under climate-driven and extreme hydrological stressors, as well as mitigation strategies. Studies were selected using targeted keywords including “THM,” “disinfection,” “water quality,” and “climate impacts.” Findings reveal four thematic clusters: characterization of disinfection by-products, optimization of treatment technologies, preventive NOM control, and mechanistic studies of THM formation. Advanced oxidation processes, hybrid membranes, adsorption, and alternative disinfectants frequently achieve over 80% removal efficiency. Preventive measures targeting NOM reduction before disinfection emerge as the most sustainable, especially under fluctuating water conditions. Nevertheless, post-treatment methods such as aeration and advanced adsorption enhance resilience to episodic contamination. Protecting drinking water requires integrating preventive and advanced technologies with adaptive regulations that address variable raw water quality, ensuring compliance and progress toward Sustainable Development Goal 6: Clean water and sanitation . • Climate change increases THM formation risk in drinking water treatment systems. • Review identifies four key research clusters on THM mitigation technologies. • Preventive NOM removal is the most sustainable strategy under climate stress. • Regulatory gaps and climate variability demand adaptive water treatment policies.