Scientists Raise Questions About How PEX Pipes Affect Water

By Sara Jerome, @sarmje

Plastic pipes used in water systems are raising concern among some scientists about the potential for leaching chemicals into tap water.

Andrew Whelton, an environmental engineer at Purdue University, is studying the impact of plastic piping material known as cross-linked polyethylene, or PEX, on tap water, according to AlterNet.

Cheap, long-lasting, and easy to install, PEX is used in 60 percent of new construction projects for delivering water into buildings, presenting an alternative to copper, Alternet reported. PEX prices can be up to 75 percent lower than copper prices, the report said.

Plastic pipes, including PEX, are under consideration for use in Flint, MI, as the city tries to replace lead water lines, according to Crain's Detroit Business.

But Whelton said scientists are still making sense of the data around this new kind of pipe. Already, research shows that PEX pipes can have an impact on the taste and odor of tap water as compounds escape the pipes.

"His group is also finding significant variations in what leaches out of PEX pipes, not just across brands but also among products of the same brand, and even from batch to batch of the same product — a confounding list of unknowns and potential concerns that makes it complicated to give advice to consumers who want safe plumbing materials," Alternet reported.

The plastic pipe industry defends PEX piping, standing by "the rigorous system of plumbing codes and certification standards that determine which pipes can be used in construction," the report said.

Whelton, however, says there is a lot of uncertainty around PEX piping.

"We don't have information about the chemicals that are leaching out of these pipes, and because of that, we can't make the decisions we want to make," he said.

"There have been marketing campaigns that imply we understand the safety of these products," he added. "In fact, we do not."

Whelton recently published a study examining PEX piping in Journal — American Water Works Association.

"PEX pipes caused greater odor than the polypropylene pipe and released more organic carbon as well as volatile and semi-volatile organic compounds. Water quality impacts were less after 30 days. Regulated and unregulated contaminants were found in three PEX plumbing systems. Drinking water odors were attributed to toluene, ethyl-tert-butyl ether, and unidentified contaminants," the study said.

The bottom line, scientists say, is more information is needed about how PEX piping affects drinking water.

"Does water need to be treated differently before traveling through plastic pipes than before flowing through copper? And should protocol vary depending on a region's geology, which can alter water's mineral content and subsequent reactivity?" the report asked, citing Andrea Dietrich, a water-quality expert at Virginia Tech in Blacksburg.

"Those factors haven't been explored," she said. "I just don't think the long-term data are out on PEX pipes."

To read more about what can happen to drinking water as it travels to homes and businesses visit Water Online's Drinking Water Distribution Solutions Center.

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