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Green buildings are increasingly being plumbed with crosslinked polyethylene (PEX) potable water pipe. Tap water quality was investigated at a six month old plumbing system and chemical and odor quality impacts of six PEX pipe brands were examined. Eleven PEX related contaminants were found in the plumbing system; one regulated (toluene) and several unregulated: Antioxidant degradation products, resin solvents, initiator degradation products, or manufacturing aides. Water chemical and odor quality was monitored for new PEX-a, -b and -c pipes with (2 mg/L free chlorine) and without disinfectant over30 days. Odor and total organic carbon (TOC) levels decreased for all pipes, but odor remained greater than the USA's Environmental Protection Agency's (USEPA) secondary maximum contaminant level. Odors were not attributed to known odorants ethyl-tert-butyl ether (ETBE) or methyl-tert-butyl ether (MTBE). Free chlorine caused odor levels for PEX-a1 pipe to increase from26 to75 threshold odor number (TON) on day3 and affected the rate at which TOC changed for each brand over30 days. As TOC decreased, the ultraviolet absorbance at254 nm increased. Pipes consumed as much as0.5 mg/L as Cl2 during each3 day stagnation period. Sixteen organic chemicals were identified, including toluene, pyridine, methylene trichloroacetate and2,4-di-tert-butylphenol. Some were also detected during the plumbing system field investigation. Six brands of PEX pipes sold in the USA and a PEX-a green building plumbing system impacted chemical and drinking water odor quality.
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According to a survey of U.S. state drinking water agencies released in2013 by the National Sanitation Foundation International (NSF) in cooperation with the Association of State Drinking Water Administrators (ASDWA), "48 states have legislation, regulations, or policies requiring drinking water system components to comply with, or be certified to NSF/ANSI Standard61."
Whelton points out, however, that the Standard61 test does not address several important issues. "The test assumes water will not be used from newly installed pipes for14 days," he says. "Secondly, the test involves only one type of [drinking water] disinfectant, [but] several other chemicals are used to keep water safe inside plumbing systems across the U.S." Other acceptable drinking water disinfectants include chloramine, also known as combined chlorine, as well as potassium permanganate and chlorine dioxide, according to Whelton. Whelton also points out that certain states have more stringent drinking water standards than what Standard61 considers.
"Standard61 also does not address drinking water odor, which is important to consumers," Whelton says. "The takeaway point is that many pipes that are available for construction professionals to install do not undergo testing that represents the field," he says. Because of these issues, additional research is necessary to determine how plastic pipes will behave once installed, he says.
Whelton's team has already tested how various brands of plastic pipe affect water-chemical quality and odor, most of their effort focused on cross-linked polyethylene, or PEX, plastic piping. And his results show high variability between how different brands of PEX pipe perform with respect to the number and amount of chemicals that they release into drinking water. "Some manufacturers make a fairly 'clean' product and other manufacturers make a very 'dirty' product," he says. "There is wide variability across available brands in the U.S. and there are at least three different PEX manufacturing processes."
Bryant agrees. "The variability in chemical leaching from brand to brand is extremely significant," Bryant notes. "If consumers had access to information about leaching per brand, then market forces would do the work to clean up manufacturing processes and the products," she says.
Bryant also notes the research team's findings that "many chemicals that end up in your water may not be material 'ingredients' per se." They may be reactants between material ingredients or between water and disinfectants, or they may be by-products of the manufacturing process. "This tells us that while the disclosure of material ingredients… is an important first step, it does not fully capture the impact of piping or other water-contact materials on water quality," she says. (The newest edition of the U.S. Green Building Council's Leadership in Energy and Environmental Design [LEED] rating system requires this type of disclosure, Bryant points out).
When the researchers examined drinking water piped through eight brands of PEX pipe, they found ethyl- tert -butyl ether (ETBE), which is a chemical that is produced as a by-product of PEX pipe manufacturing, according to Whelton. Even though there are no federal guidelines on safe levels of ETBE, "certain states have decided to impose their own limits," Whelton notes. The levels of ETBE discovered by the researchers in the pipes exceeded the health limits established by both New Hampshire and New York, he says. "That's an important finding because to my knowledge, the pipes that are being sold and marketed today are not marketed for different states." Most are promoted as having been tested by the NSF's Standard61, but this method does not test for ETBE, he points out.
Whelton and his team also tested the plastic pipes for odor over the course of a30-day period. "We found that on day30, odor levels were equal to or less than those on day3, but all pipes exceeded the EPA's recommended drinking water odor level," he noted. "Odor is an aesthetic standard, it's not a health-based standard," Whelton points out. "But …water companies across the United States strive to provide clean, safe, and pleasing water to people…[and] the data we have show building plumbing piping can drastically change the quality of that water."
Bryant, Whelton, and Stenson have drafted a pilot credit for the LEED rating program. The requirement that manufacturers disclose the ingredients of their building products "is the backbone" of the credit, Bryant says. "The credit goes a step further, requiring disclosure of the NSF Standard61 extraction reports, which analyze compounds in water that have been in contact with these pipes," Bryant says. "The credit also includes specific considerations for preventing lead contamination in metal piping, and addresses best practices to prevent pathogen proliferation in all piping types."
"Many green building organizations and the USGBC in particular, have been quite embattled as they try to promote consumers' right to know more about the materials in their buildings," Bryant says. "The discussion has been likened to the first debates around nutritional labeling for food products. In those debates, manufacturers argued that disclosure would ruin their businesses, that competitors would steal their 'secret recipes,' etc. It's very similar to the discussion we're having today about building materials.
Thanks for the invitation
Very sorry for not answering the
question , where outside my specialized vocational
Good Morning all, Agreed with colleagues answers Mr Jaafer & Mr Omer
Thank you my dear friend for invitation ,,, I agree with your answer and with omer and I have to add also that there are Previous international studies have shown that plastic pipes can release substances that give an unwanted taste and odour to drinking water. It has also been suggested that some of these substances may be carcinogenic.
The aim of the study by the Norwegian Institute of Public Health was to investigate whether leakage products from these pipes are harmful to health and if they affect the taste and odour of drinking water. These leakage products consist of residues of additives used during production to give plastic pipes their desired properties, as well as any subsequent breakdown products.The study showed:.There are no health risks associated with drinking water from PEX pipe
A few types of PEX-pipe may cause prolonged undesirable taste and odour if the water remains in pipes over time. Although the taste and odour usually dissipate with use, water from two of the PEX types still had an unpleasant smell and taste after a year.The level of volatile organic compounds that leaked from new PEX pipes was generally low .The level was further reduced with use . No correlation was found between production method and leaking products Ten different types of PEX pipes available in the Norwegian market were tested for leaching products in a standardised laboratory test. The water was in contact with the tubes for72 hours.
Three different manufacturing methods produce pipes known as PEX-a, PEX-b or PEX-c. These methods use slightly different additives, but this study found no correlation between production method and leakage products. 2.4-di-tert-butyl-phenol and methyl-tert-butyl ether (MTBE) were two of the most commonly occurring substances detected in the water in the experiments.
For three types of new pipe, MTBE was detected in higher concentrations than the U.S. government's recommended limits for taste and odour of drinking water (USEPA), but the values were reduced to below this limit after the tubes had been in use for a while
tanks you answer your equation and Mr. omer .
Thanks for invitation
Agree with members
Very much agreed with answers given by Mr. Omer and Mr. Jaafer
using activated charcoal we can release the contaminants and odor from water
