Water Contaminants in Green Buildings

Several Types of Plastic Pipes in Eco-friendly Green Buildings Have Been Found to Leach Chemicals Into Drinking Water that Can Cause Odors Exceed Health Standards

Several types of plastic pipes in eco-friendly green buildings in the United States have been found to leach chemicals into drinking water that can cause odors and sometimes exist at levels that may exceed health standards.

Buildings are being plumbed with many types of plastic drinking waterpipes. These include crosslinked polyethylene (PEX), high-density polyethylene (HDPE), polyvinylchloride (PVC), chlorinated PVC (cPVC) and polypropylene (PP) pipes, said Andrew Whelton, an assistant professor ofcivil engineeringin Purdue University's Lyles School of Civil Engineering and Division of Environmental and Ecological Engineering.

Plastic pipes are generally less expensive, lighter and easier to install than metal pipes. A 2012 comparison showed PEX pipe was the least expensive among plastic pipes, costing 43 cents per foot compared to the most expensive metal, copper pipe, at $2.55 per foot.

Thousands of dollars can be saved during construction by installing plastic instead of metal plumbing systems, and proponents assert plastic pipes require less energy to manufacture - generating less carbon dioxide compared to metal pipes - ostensibly making them a good fit for green buildings.

"Little is known about the degree to which plastic pipes sold in the U.S. affect drinking water quality," Whelton said.

He will detail research findings in a presentation during the 2014 U.S. Green Building Council's Greenbuild International Conference & Exposition on Friday (Oct. 24) in New Orleans with Rebecca Bryant, managing principal of Watershed LLC of Fairhope, Alabama. Some testing results were published online in September in the journal Water Research . There, the researchers describe drinking water impacts caused by six brands of PEX pipes available in the United States.

In the September study, drinking water was tested from a PEX plumbing system in a "net-zero energy" building in Maryland six months after the system had been installed. The testing revealed the presence of 11 chemicals that were PEX pipe ingredients and ingredient degradation products. Research with PEX pipes in the laboratory also showed that six brands caused drinking water to exceed the U.S. Environmental Protection Agency's maximum recommended drinking water odor limit, Whelton said. The U.S. EPA's maximum drinking water odor limit is a "threshold odor number" of 3, or 3 TON. Compliance is voluntary because the standard is based on aesthetic - not health - considerations.

Odor and chemical levels were monitored with and without chlorine treatment over a 30-day period for the six pipe brands. Chlorine, the most popular disinfectant chemical used in the United States, protects drinking water from disease-causing organisms as it travels to the tap. When chlorine reacted with chemicals leached by theplastic pipes, odor levels for one brand of PEX pipe tripled. While the total mass of chemicals leached by PEX pipes was found to decline after 30 days of testing, odors generally continued as the pipes aged, Whelton said.

A general assumption in the United States is that chemicals responsible for drinking water odors pose no health dangers. Although, several chemicals found in the plumbing research have regulated health limits, and one PEX pipe brand caused drinking water to exceed the ethyl-tert-butyl ether (ETBE) drinking water health standard. ETBE is a PEX pipe manufacturing byproduct with drinking water standards in New Hampshire and New York state.

Source: Phys.Org

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Taxonomy

• Environment
• Pollution
• Drinking Water