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1. Critical Review: Propensity of Premise Plumbing Pipe Materials to Enhance or Diminish Growth of Legionella and Other Opportunistic Pathogens

   https://doi.org/10.3390/pathogens9110957  

   Cullom, Abraham C.; Martin, Rebekah L.; Song, Yang; Williams, Krista; Williams, Amanda; Pruden, Amy; Edwards, Marc A. (November 2020, Pathogens)

   null (Ed.)

   Growth of Legionella pneumophila and other opportunistic pathogens (OPs) in drinking water premise plumbing poses an increasing public health concern. Premise plumbing is constructed of a variety of materials, creating complex environments that vary chemically, microbiologically, spatially, and temporally in a manner likely to influence survival and growth of OPs. Here we systematically review the literature to critically examine the varied effects of common metallic (copper, iron) and plastic (PVC, cross-linked polyethylene (PEX)) pipe materials on factors influencing OP growth in drinking water, including nutrient availability, disinfectant levels, and the composition of the broader microbiome. Plastic pipes can leach organic carbon, but demonstrate a lower disinfectant demand and fewer water chemistry interactions. Iron pipes may provide OPs with nutrients directly or indirectly, exhibiting a high disinfectant demand and potential to form scales with high surface areas suitable for biofilm colonization. While copper pipes are known for their antimicrobial properties, evidence of their efficacy for OP control is inconsistent. Under some circumstances, copper’s interactions with premise plumbing water chemistry and resident microbes can encourage growth of OPs. Plumbing design, configuration, and operation can be manipulated to control such interactions and health outcomes. Influences of pipe materials on OP physiology should also be considered, including the possibility of influencing virulence and antibiotic resistance. In conclusion, all known pipe materials have a potential to either stimulate or inhibit OP growth, depending on the circumstances. This review delineates some of these circumstances and informs future research and guidance towards effective deployment of pipe materials for control of OPs. 

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2. Pilot‐Scale Analysis of Stagnation and Flushing in Premise Plumbing

   https://doi.org/10.1002/aws2.70012  

   Hogue, Derek; Steele, McKenzie; Boyer, Treavor_H (January 2025, AWWA Water Science)

   ABSTRACT Research has demonstrated that water quality degrades in commercial and institutional (C&I) building premise plumbing leading to increased risk to consumers. This study aimed to bridge the gap between real premise plumbing systems and theory by using a pilot scale pipe rig representative of C&I premise plumbing. The research examined changes in key water quality parameters, including chlorine, copper, trihalomethanes (THMs), and cellular ATP (cATP) across different flushing and stagnation conditions. Results indicated significant degradation during periods of stagnation found in real premise plumbing, with reductions in chlorine levels and increases in copper and THM concentrations. Conversely, flushing effectively renewed water quality, though the extent varied with system size and flow dynamics. Correlations were found between key water quality variables. The findings emphasize the need for strategic water management practices to mitigate risks associated with poor water quality in building plumbing systems. 

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3. A Critical Review on the Factors that Influence Opportunistic Premise Plumbing Pathogens: From Building Entry to Fixtures in Residences

   https://doi.org/10.1021/acs.est.2c04277  

   Logan-Jackson, Alshae’ R.; Batista, Marylia Duarte; Healy, William; Ullah, Tania; Whelton, Andrew J.; Bartrand, Timothy A.; Proctor, Caitlin (April 2023, Environmental Science & Technology)

   Residential buildings provide unique conditions for opportunistic premise plumbing pathogen (OPPP) exposure via aerosolized water droplets produced by showerheads, faucets, and tubs. The objective of this review was to critically evaluate the existing literature that assessed the impact of potentially enhancing conditions to OPPP occurrence associated with residential plumbing and to point out knowledge gaps. Comprehensive studies on the topic were found to be lacking. Major knowledge gaps identified include the assessment of OPPP growth in the residential plumbing, from building entry to fixtures, and evaluation of the extent of the impact of typical residential plumbing design (e.g., trunk and branch and manifold), components (e.g., valves and fixtures), water heater types and temperature setting of operation, and common pipe materials (copper, PEX, and PVC/CPVC). In addition, impacts of the current plumbing code requirements on OPPP responses have not been assessed by any study and a lack of guidelines for OPPP risk management in residences was identified. Finally, the research required to expand knowledge on OPPP amplification in residences was discussed. 

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4. Phosphate-Based Corrosion Inhibition in Drinking Water Systems and Effects on Disinfectant Decay and Biofilm Growth

   https://doi.org/10.1089/ees.2023.0065  

   Huang, Conghui; Ginn, Timothy R.; Clark, Gemma G.; Zaki, Farzana R.; Won, Jungeun; Boppart, Stephen A.; Nguyen, Thanh H. (October 2023, Environmental Engineering Science)

   Catherine Peters (Ed.)

   Disinfectant decay by biofilms in distribution networks during stagnation can allow opportunistic pathogens' transmission and thus compromise drinking water safety. Applying phosphate-based corrosion inhibitors to the system can exacerbate disinfectant decay by providing nutrients to biofilms growing inside premise plumbings. In this study, we evaluate the impacts of corrosion inhibitors on biofilms' structural and chemical properties that form in premise plumbing, and the resulting implications for disinfectant decay. Two commonly used phosphate-based (phosphate blends and phosphate) corrosion inhibitors were added separately to simulated drinking water for biofilm development over 1 to 2 years. Optical coherence tomography (OCT) imaging showed that the studied biofilms' thickness, porosity, and porous structure did not change after exposure to free chlorine for 24 h or monochloramine for 120 h. Compared with groundwater biofilms, phosphate-based biofilms had the highest overall porosity due to their many connecting channels. The phosphate-based biofilms consumed free chlorine or monochloramine at a faster rate than groundwater biofilms. Experimental results showed that phosphate-based biofilms consumed more monochloramine after 96 h of contact than other biofilms. A separate set of experiments involving disinfectant decay with suspended biomass material, together with the OCT results, provided parameters for a simplified quasi-first-order reaction–diffusion model so that predictive modeling of decay in biofilms under stagnation conditions could be attempted without parameter fitting. The biofilm modeling results provided a close estimate for free chlorine decay while underestimating monochloramine decay. In agreement with the experimental results, the model results indicate that the phosphate-based biofilms led to slightly faster free chlorine consumption and monochloramine consumption than groundwater biofilms and indicate that diffusion limitation imposed by biofilm pore structure on disinfectant decay is important. The study results suggest that using phosphate-based corrosion inhibitors may lead to a rapid depletion of residual disinfectant during stagnation in the presence of biofilms. 

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5. Impact of physical and chemical parameters on square wave anodic stripping voltammetry for trace Pb ²⁺ detection in water

   https://doi.org/10.1039/d2an00724j  

   Rahm, Connor E; Gupta, Pankaj; Gupta, Vandna K.; Huseinov, Artur; Griesmer, Ben; Alvarez, Noe T. (June 2022, The Analyst)

   Exposure to lead, a toxic heavy metal, in drinking water is a worldwide problem. Lead leaching from lead service lines, the main contamination source, and other plumbing materials is controlled by the plumbosolvency of water. Square wave anodic stripping voltammetry (SWASV) has been greatly explored as a rapid and portable technique for the detection of trace Pb 2+ ions in drinking water. However, the impact of water quality parameters (WQP) on the SWASV technique is not well understood. Herein, SWASV was employed to detect 10 μg L −1 Pb 2+ and determine trends in the stripping peak changes in simulated water samples while individually varying the pH, conductivity, alkalinity, free chlorine, temperature, and copper levels. The pH and conductivity were controlled using the buffer 3-( N -morpholino)propanesulfonic acid (MOPS), and NaNO 3 , respectively and kept at pH = 7.0 and conductivity = 500 μS cm −1 when exploring other WQPs. The working electrode, a gold-nanoparticle-modified carbon nanotube fiber cross-section (AuNP-CNT f -CS) electrode provided sufficiently sharp and prominent peaks for 10 μg L −1 Pb 2+ detection as well as good reproducibility, with a relative error of 5.9% in simulated water. We found that conductivity, and temperature had a proportional relationship to the peak height, and pH, alkalinity, free chlorine, and copper had an inverse relationship. In addition, increasing the copper concentration caused broadening and shifting of the Pb 2+ stripping peak. At extremely low conductivities (<100 μS cm −1 ), the voltammograms became difficult to interpret owing to the formation of inverted and distorted peaks. These trends were then also observed within a local drinking water sample in order to validate the results. 

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