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Center for Plumbing Safety

Peer-Reviewed Publications

Summary

The Tubbs Fire (2017) and Camp Fire (2018) are the first known wildfires where widespread drinking water chemical contamination was discovered in the water distribution network and not in the source water after the fire. In both disasters, drinking water exceeded state and federal government‐defined exposure limits for several volatile organic compound (VOC) contaminants (e.g., benzene at 40,000 µg/L [Tubbs] and >2,217 µg/L [Camp]). This work outlines factors that influence wildfire‐induced drinking water quality threats based on the findings from these two fires and explores related scientific and policy issues. For example, certain plastics in the network may serve as a primary VOC source through in situ plastic pyrolysis. Depressurization of the distribution network likely transported contaminated water that subsequently contaminated undamaged infrastructure. As wildfires at the wildland–urban interface are likely to occur more frequently, greater scientific evidence is needed to guide agency responses that will better protect public health.

Summary

The unprecedented number of building closures related to the coronavirus disease (COVID‐19) pandemic is concerning because water stagnation will occur in many buildings that do not have water management plans in place. Stagnant water can have chemical and microbiological contaminants that pose potential health risks for occupants. Health officials, building owners, utilities, and other entities are rapidly developing guidance to address this issue, but the scope, applicability, and details included in the guidance vary widely. To provide a primer of large building water system preventative and remedial strategies, peer‐reviewed, government, industry, and nonprofit literature relevant to water stagnation and decontamination practices for plumbing was synthesized. Preventative practices to help avoid the need for recommissioning (e.g., routine flushing) and specific actions, challenges, and limitations associated with recommissioning were identified and characterized. Considerations for worker and occupant safety were also indicated. The intended audience of this work includes organizations developing guidance.

  • Formation and sorption of trihalomethanes from cross-linked polyethylene pipes following chlorinated water exposure. Environmental Science: Water Research and Technology. 2020. Available at https://doi.org/10.1039/D0EW00262C.

Summary

In recent years, cross-linked polyethylene (PEX) pipes have become more commonplace in building plumbing. However, their presence can strongly impact water quality by leaching organic carbon and sorbing contaminants, to and from the water supply, respectively. This study assessed how these processes could further impact concentrations of disinfection by-products (DBPs) and specifically trihalomethanes (THMs) when exposed to chlorinated water. One brand of three different PEX types (PEX-a, PEX-b, and PEX-c) were exposed to synthetic water, which was subsequently chlorinated over 120 h under varying water quality conditions (e.g. temperature, pH, bromide concentration, and free chlorine dose). Results indicated that THM formation was fairly modest for all three PEX types at 22 °C but increased by a factor of ∼2 at 55 °C for the PEX-a pipe. Other water quality conditions exhibited more limited effects. Pipe-storage time strongly affected leached organic carbon levels but did not affect THM formation. THM sorption also occurred for all three PEX types and was similarly controlled by temperature. Sorption data fit well to a kinetic adsorption model. Combined effects of THM formation and sorption at 22 °C generated no aqueous phase THMs, although this effect was not similarly examined at 55 °C. These results suggest that sorption may mitigate the effects of THM formation if PEX pipes continue to reside downstream of where formation occurred, but this may not be the case if other pipe types (e.g. metal pipes) are present. Overall, these findings have important regulatory consequences since current THM monitoring may or may not account for building PEX plumbing.

  • Knowledge-gaps and risks associated with premise plumbing drinking water quality. AWWA Water Science. 2020. Available at https://doi.org/10.002/aws2.1177 or contact us for a copy.

Summary

Plumbing and public health sector professionals were convened at the start of our $2 million national priority building plumbing research study in 2017. A series of needs were identified to improve the understanding of and the ability to predict water safety at building water outlets. Issues associated with low water use in buildings were identified. Some activities identified in this plumbing and public health sector event are actively being addressed by the ongoing multi-institution study with Purdue University, Michigan State University, Manhattan College, Tulane University, and University of Memphis. The gap study also helped inform a subsequent US National Institute for Standards and Technology meeting which further identified building water plumbing research needs.

Summary

Water quality at cold and hot water faucets was characterized during 1 year in a highly instrumented residential home. More than 2.4 billion online monitoring records were collected for fixture flow and temperature and online water quality monitoring was conducted as water entered the building too. During the year, water samples at the home were collected for 58 days - before water entered the building and inside the building for cold and hot water. More than 222,000 labor hours were needed by 30 Purdue University and Michigan State University students, faculty, and staff to conduct this monitoring - not including data analysis and interpretation.

Key Findings:

  • Drinking water quality entering the building varied by season.
  • For 10.3% of the year's water sampling events, drinking water entering the building did not contain a detectable chlorine disinfectant residual.
  • Inside the building, water stagnation time varied seasonally and across fixtures. Water at the kitchen sink in the Summer had different characteristics than water in the Winter. For example, cold water at the bathroom sink had different characteristics than water at the kitchen sink.
  • Water pH also consistently and significantly increased in the plumbing from 7.5 to 9.4, and total trihalomethane (TTHM) levels increased up to 89%.
  • Drinking water organic carbon entering the building was consistent (0.5-0.6 mg/L), but much greater variability was found inside the building for cold (0.4-61.0 mg/L) and hot water (0.5-4.7 mg/L).
  • Models are needed to predict chemical water quality at the faucet using service line water quality results and plumbing design and operational information. Building water sensor technology innovations are also needed.

Summary

Six-month old galvanized iron pipes (GIPs) and downstream crosslinked polyethylene (PEX) pipes were exhumed from a residential home. Follow-up bench-scale experiments revealed that metal levels in the drinking water did not always predict metal loadings on plastic pipe surfaces. This study highlights potential downstream plastic pipe degradation and metal deposition, which may cause plumbing problems and failures for building owners, inhabitants, and water utilities.

Key Findings:

  • CuO, Cu(OH)2, FeOOH, Fe2O3, and MnO2 were found on exhumed PEX pipe surfaces.
  • Moderately aggressive water at 55 °C resulted the greatest metal loading on plastic surfaces.
  • PEX pipes exposed to hot water released more organic carbon than cold water.
  • PEX pipes connected to copper and brass had the greatest plastic surface oxidation.

Summary

Testing was conducted in a newly renovated single-family home for the first 4 months of use. The plumbing system was PEX type A pipe installed using trunk-and-branch design. More than 64 million data points were collected related to fixture water use and were analyzed. Drinking water sampling was conducted periodically at various locations in the home. Water was tested for both chemical, microbiological, and odor characteristics.

Key Findings:

  • During the study, the maximum fixture water stagnation time was 72 hours.
  • Hot water contained greater levels of bacteria and organic carbon than cold drinking water.
  • Chemical and bacteria levels varied across fixtures within the building.
  • Pb, Fe, and Zn exceeded EPA standards, but only at the least frequently used (and monitored) fixture in the basement.

Summary

Heavy metal abundance and scale morphology for cross‐linked polyethylene (PEX) plastic pipes and pipe oxidative condition were examined in a one‐year‐old residential plumbing system.

Key Findings:

  • Metals found on the plastic pipes (Al, Ca, Co, Cu, Pb, Mg, Mn, Ni, Se, Zn) were corrosion products from drinking water distribution and plumbing materials and were present in the source water.
  • Fe was the most abundant contaminant on pipes.
  • Plastic served as a nucleation site for Fe crystal growth and expedited crystal formation.
  • Plastic plumbing pipes can adsorb metals that have health and aesthetic drinking water limits, and additional work is needed to understand the conditions that affect metal accumulation and release.