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Impact of cold-water premise plumbing on the fate and associated additive toxicity of disinfection byproducts
Journal article   Open access   Peer reviewed

Impact of cold-water premise plumbing on the fate and associated additive toxicity of disinfection byproducts

Sheldon V. Masters, Timothy A. Bartrand, Kylie M. Boenisch-Oakes, Yun Yu, Marylia Duarte Batista, Audrey Young Keightley, Dienye L. Tolofari, Chad J. Seidel and R. Scott Summers
Water research X, v 30, 100459
01 Jan 2026
DOI: https://doi.org/10.1016/j.wroa.2025.100459
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https://doi.org/10.1016/j.wroa.2025.100459View
Published, Version of Record (VoR) Open

Abstract

Calculated additive toxicity Haloacetic acid Haloacetonitriles Trihalomethane
•Water use frequency and disinfectant type dominate DBP fate at the tap.•Low-use stagnation reduced HANs and DBP calculated toxicity by up to 80% in pipe racks.•High-use conditions increased calculated toxicity by 25–50% across all pipe types.•Broader DBP analysis revealed unregulated HALs dominate calculated toxicity after stagnation.•The decline in CAT during stagnation was accompanied by increased HPCs across all pipe materials, highlighting the need to balance chemical and microbial risks in premise plumbing. Disinfection byproducts (DBPs) can transform within building plumbing systems, altering both concentrations and toxicity at the point of use. This study evaluated how pipe material (copper, PEX, PVC), pipe diameter, and water use frequency affect the fate of four regulated trihalomethanes (THM4), nine haloacetic acids (HAA9) and four haloacetonitriles (HAN4) using controlled pipe racks operated for one year under chlorinated and chloraminated conditions. The calculated additive toxicity (CAT) metric for these DBP groups was also evaluated. Random Forest analysis revealed that water use frequency and disinfectant type were the strongest predictors of DBP occurrence and CAT with pipe material and size playing secondary roles. Under low-use conditions, HAN4 concentrations decreased by 60–90%, resulting in a 40–80% reduction in CAT relative to feed water, primarily due to the degradation of nitrogenous DBPs. In contrast, high-use conditions increased CAT by 25–50% across all pipe types. Complementary batch experiments, using copper and PEX pipes, expanded the DBP scope to 52 regulated and unregulated species and showed that, while HANs again declined, overall CAT did not decrease due to elevated levels of unregulated DBPs, particularly haloacetaldehydes which dominated CAT. These findings underscore the limits of relying on regulated DBPs or narrow toxicity metrics and suggest that whole-water assays offer a stronger framework for assessing health risk changes in plumbing systems. The apparent decline in DBP toxicity during stagnation coincided with much higher microbial activity (HPCs) across all pipe materials, emphasizing the challenge of balancing chemical and microbial risks in premise plumbing. [Display omitted]

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UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#3 Good Health and Well-Being
#6 Clean Water and Sanitation

Source: SDGs in the Output

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Collaboration types
Domestic collaboration
Web of Science research areas
Engineering, Environmental
Environmental Sciences
Water Resources
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