PEX and PP Water Pipes: Assimilable Carbon, Chemicals, and Odors

Abstract

Eleven brands of plastic drinking water pipe were evaluated for assimilable organic carbon (AOC) release at 23°C for 28 days: polyvinyl chloride, high‐density polyethylene, polypropylene (PP), and cross‐linked polyethylene (PEX) pipes. Three of eight PEX pipe brands exceeded a 100 µg/L AOC microbial regrowth threshold for the first exposure period, and no brands exceeded this value on day 28. No AOC increase was found for PP or PEX‐a1 pipes; the remaining pipe brands contributed marginal AOC levels. Pipe water quality impacts were more fully evaluated for two PEX‐b brands and one PP brand. PEX pipes caused greater odor than the PP 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.

Towards a probiotic approach for building plumbing – nutrient-based selection during initial biofilm formation on flexible polymeric materials

“…One very practical relevance of biofilm growth and selection discussed above is the first colonization of drinking water plumbing systems during the commissioning of new buildings. Here, a wide variety of synthetic plumbing materials 34,35 provides biodegradable organic carbon 36,37 to complex drinking water microbial communities 38,39 . The consequence is biofilm formation and development in the plumbing system, which ultimately affects the microbiological quality of the drinking water 34,40 .…”

The role of surface copper content on biofilm formation by drinking water bacteria

“…54 Nevertheless, copper expensive cost is one of the main reasons to increase the use of plastic materials in plumbing systems. 55,56 Copper leaching to drinking water and its possible negative effects on the water quality and public health also contributed to the misuse of this material. 22,54 Nevertheless, the choice between copper or plastic pipes is still controversial.…”

“…57 Although plastic pipes have lower installation costs, they usually have a shorter life-time and can be responsible for the leaching of some chemicals to the drinking water, changing the water characteristics and causing some concern to consumers' health, including potential carcinogenic effects and the favoring the growth of pathogens. 26,55,58 The present work aims to screen alloys with different copper contents (0, 57, 79, 87, 96 and 100%) in order to understand the possibility of using less expensive copper materials in plumbing systems to reduce biolm developmentguaranteeing the microbial and chemical quality of the delivered water. The corrosion rate of each material was also evaluated as well as copper leaching to the bulk water.…”

“…Nevertheless, the use of plastics is controversial as they are associated to chemical leaching to the drinking water and changes in water odor. 26 The possibility of using less expensive copper alloys in plumbing systems would certainly boost the interest for their use. However, research on the use of copper alloys in plumbing systems is scarce.…”

Experiences of Green Building Professionals With Water‐Related Systems

“…Some technologies have been studied systematically, especially with regard to opportunistic pathogens colonizing water heater systems (Brazeau & Edwards 2011, Mathys et al 2008, Bagh et al 2004, Codony et al 2002), and similar possible pathogen problems have been found with rainwater harvesting (Kim et al 2016). There has been a study of cross‐linked polyethylene (PEX) and polypropylene pipes suggesting possible issues with pathogens, odors, and emissions (Connell et al 2016). Other work has been done reviewing literature on degraded water quality as affected by increased water age in pipes.…”