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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.