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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. Degradation of Plastic Pipes in Building Plumbing Systems: Coupled Effects on Heavy Metal Transport and Water Chemistry

   https://doi.org/10.1002/clen.70079  

   Ghoochani, Shima; Datta, Dibya Kanti; Bashir, Atif; Salehi, Maryam (December 2025, CLEAN – Soil, Air, Water)

   ABSTRACT Due to the potential occurrence of heavy metals in tap water, it is critical to examine their interactions with plastic potable water pipe surfaces, as these pipes may undergo physicochemical degradation induced by residual disinfectants over time. Thus, this study investigated the influence of plastic pipe degradation and water alkalinity on the release of Pb, Cu, and Zn from crosslinked polyethylene type A (PEX‐A) pipes after they underwent heavy metal accumulation experiments. For this purpose, an accelerated aging process was conducted by exposing pipes to a solution with a total chlorine concentration of 2500 mg L⁻¹at 70°C for 6 days. Disinfectant decay and organic leaching characteristics were examined for new and aged pipes in both cold and hot water. Surface chemistry analyses of pipes after accelerated degradation revealed the formation of oxidized carbon surface functional groups and etched‐like surface morphology. Aged pipes demonstrated higher heavy metal accumulation in the presence of alkalinity compared to conditions without alkalinity. Cu accumulation was found to be the most prominent, followed by Pb and Zn. The new PEX‐A pipes released more metals than aged PEX‐A pipes at pH 6.0. This pH was selected to assess the sensitivity of metal release to pH changes under more aggressive water chemistry. For hot water, both new and aged PEX‐A pipes exhibited a significant reduction in total chlorine residual concentration after 12 h, with aged pipes showing a faster chlorine decay rate. Hot water also promoted organic leaching from both new and aged pipes at pH 6.0. 

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3. Studying the impacts of non-routine extended schools' closure on heavy metal release into tap water

   https://doi.org/10.1039/d2ew00149g  

   Ghoochani, Shima; Salehi, Maryam; DeSimone, Dave; Salehi Esfandarani, Mitra; Bhattacharjee, Linkon (June 2022, Environmental Science: Water Research & Technology)

   The extensive school closures due to the unprecedented COVID-19 pandemic resulted in prolonged water stagnation within schools' plumbing for longer durations than routine schools' holidays and summer breaks. With many of the U.S. schools suffering from problems of lead (Pb) in potable water for decades, the extended water stagnation caused by schools' closure has raised significant concerns regarding the schools' water safety. Thus, this research was conducted to evaluate the resiliency of schools' potable water plumbing toward the interruption caused by the COVID-19 pandemic. For this purpose, the impact of extended water stagnation on heavy metal release into water samples collected from fixtures with and without known lead problems in 25 schools within a school district in Tennessee was investigated. The results revealed a significant increase in the median Pb concentration due to the extended water stagnation. Furthermore, elevated levels of Fe, Zn, and Cu were released from both problematic and nonproblematic fixtures into tap water. Estimation of children's blood lead level (BLL), assuming the consumption of prolonged stagnated water, revealed an increased risk of elevated BLLs (>5 μg dL −1 ). To better identify the potential sources of lead release within schools, a combination of plumbing investigation and sequential water sampling was conducted. The lead-containing fixtures, connecting plumbing, and interior plumbing were found as the possible sources contributing to the lead release into water. Implementation of remediation actions reduced the lead release into tap water to less than 3.4 μg L −1 in the target fixtures. 

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4. 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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5. Solar distillation of human urine to recover non-potable water and metal phosphate mineral

   https://doi.org/10.2166/wst.2023.218  

   Bucholtz, Pippin; Steele, McKenzie; Tripathi, Vedika; Graham, Cole; Crane, Lucas; Boyer, Treavor H (July 2023, Water Science & Technology)

   Human urine is a readily available nutrient source that can complement commercial fertilizer production, which relies on finite mineral resources and global supply chains. This study evaluated the effectiveness of a simplified solar distillation process for urine to recover phosphorus (P) and nitrogen for agricultural use and water for non-potable purposes. Synthetic fresh, synthetic hydrolyzed, real fresh, and real hydrolyzed urine were exposed to direct sunlight for 6 h in a simple distillation apparatus, which produced distillation bottoms and distillate. Metal phosphate precipitation in the distillation bottoms was evaluated to recover P. The non-potable water was recovered as distillate. Hydrolyzed urine recovered more metal phosphate solid in the distillation bottoms and had a higher conductivity in the distillate than fresh urine. Hydrolyzed urine also achieved greater distillate volume recovery than fresh urine. Hydrolyzed urine had a greater presence of UV-absorbing organics in the distillate than fresh urine and therefore produced a lower-quality product water. There was no significant correlation between the daily high air temperature and the volume of distillate recovered. This study provides a comprehensive data set on simplified solar distillation of human urine considering the fate of nutrients and water for different types of urine. 

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