In an article published on May 2, 2016 by the magazine Ensia, freelance writer Emily Sohn reports on a plastic water piping material called PEX and how it may affect drinking water quality and health. PEX stands for cross-linked polyethylene and is used in over 60% of new construction projects in the U.S., Sohn writes. It is lightweight, flexible, comparatively cheap, easy to transport and install, and long lasting. However, it is still largely unknown how PEX affects the water that runs through it. Andrew Whelton, environmental engineer at Purdue University, U.S., and his research group found that various substances can leach from PEX pipes into water, potentially leading to bad smell or bad taste of the water. The leachables can vary significantly across different brands of PEX, but also among products of the same brand, or even from batch to batch of the same product. Also, Whelton and colleagues found that some PEX varieties may release enough assimilable organic carbon in order for harmful microbes to grow inside the pipes. Even though PEX pipes are rigorously tested to comply with national plumbing codes and the international standards imbedded in them, many unknowns remain about PEX such as its actual composition, Whelton points out. He highlights the importance of codes and standards, but notes that guidelines should specify more chemicals, “including some that make water smell bad enough to be undrinkable (even if they still meet health standards) and others that could allow illness-causing bacteria to flourish.”

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Emily Sohn (May 2, 2016). “What’s in those new plastic pipes delivering drinking water?Ensia