Migration of Volatile Organic Compounds (VOCs) from PEX-a Pipes into the Drinking Water during the First Five Years of Use

Abstract

A brand-new office building in Rauma, Finland, was used to study the first five years of PEX-a drinking water pipes in normal use. Both pipe material and water samples from hot and cold-water pipelines were analyzed. Migration of volatile organic compounds (VOC) from the PEX-a pipes into the drinking water was observed to decrease rapidly during the first months. Deterioration of the PEX-a material was observed to take place due to the wearing down of organic antioxidants added into the PEX-a material during the manufacturing of the pipes. Tert-butyl alcohol (TBA) concentrations were high during the first months after commissioning of use. The stagnation time of the drinking water in contact with the PEX-a material before the actual water sample was taken had a major impact on analyzed migration of organic compounds. Hence, the amount of organic compounds able to migrate from materials into the drinking water will increase when the stagnation time increases. In this study, the water samples were taken after overnight stagnation, whereas in normal use it is advisable to run water properly before drinking it. Instructions will be needed for the average user to avoid harmful health effects.

The benefits of flushing for mitigating Legionella spp. in non-chlorinated building plumbing systems

“…Legionella occurrence was also higher in the PEX-A biofilms (83 %) than in the copper biofilms (61 %). Higher biofilm growth in PEX-A could be attributed to the leaching of organic carbon into the bulk water from the PEX-A during stagnation (Pelto-Huikko et al, 2021) and also to the antimicrobial properties of copper (Gomes et al, 2020). However, no effect of pipe material on planktonic microbe concentrations was observed during this study, likely because more than 90 % of the plumbing system was comprised of copper pipes except for the 1 m distal branches.…”

Impact of the surface aging of potable water plastic pipes on their lead deposition characteristics

“…7). 10 Thus, at a lower range of Pb concentrations, the pipe age, and thus surface oxidation, influences the adsorption of Pb species. However, by increasing the initial Pb concentrations, we increased the layers of insoluble Pb species that precipitate onto the pipe surface, therefore we did not find a significant difference in the maximum Pb surface loadings for the new and aged PEX-A and HDPE pipes.…”

“…[7][8][9] Antioxidants such as 2,4-di-tert-butylphenol, and 2,6-di-tert-pbenzoquinone are added to PEX pipes during the manufacturing process to prevent their oxidation by chlorinated drinking water. 10 However, leaching of these antioxidants out of the plastic pipes during the first couple of years of their service makes them susceptible to oxidation by chlorine residues. 7,8 Field investigations have demonstrated the formation of carbonyl (>CO) and ether (>C-O-C<) functional groups on the surface of PEX pipes as a result of exposure to chlorinated water.…”