Plastic pipes have been and are being installed downstream of metal drinking water plumbing components. Prior research has suggested that such pipe configurations may induce plastic pipe degradation and even system failure. To explore the impact of upstream metal plumbing components on downstream plastic pipes, field- and bench-scale experiments were conducted. Six month old galvanized iron pipes (GIPs) and downstream crosslinked polyethylene (PEX) pipes were exhumed from a residential home. Calcium, iron, manganese, phosphorous, and zinc were the most abundant elements on both GIPs and PEX pipes. Black and yellow deposits were found on some of the exhumed PEX pipe inner walls, which were mainly copper, iron, and manganese oxides (CuO, Cu(OH)2, Fe2O3, FeOOH and MnO2). Follow-up bench-scale experiments revealed that metal levels in the drinking water did not always predict metal loadings on plastic pipe surfaces. The pH 4 water resulted in a greater amount of metals released into the bulk water, but the pH 7.5 water resulted in a greater amount of metals deposited on the PEX pipe surfaces. Hot water (55 °C) induced a greater amount of organics released and higher metal loadings on PEX pipe surfaces at pH 7.5. ATR-FTIR analysis showed that at 55 °C, PEX pipes connected to copper and brass components had the greatest oxidation functional group peak intensity (COOC, CO, and COC). This study highlights potential downstream plastic pipe degradation and metal deposition, which may cause plumbing problems and failures for building owners, inhabitants, and water utilities.

中文翻译：

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上游金属管道组件的腐蚀会影响下游PEX管道表面的沉积物和降解。

塑料管道已经并且正在安装在金属饮用水管道组件的下游。先前的研究表明，这样的管道配置可能导致塑料管道退化甚至系统故障。为了探索上游金属管道组件对下游塑料管的影响，进行了现场和实验规模的实验。从一个住宅中挖掘出了六个月大的镀锌铁管（GIP）和下游的交联聚乙烯（PEX）管。钙，铁，锰，磷和锌是GIP和PEX管道中含量最丰富的元素。在一些已掘出的PEX管内壁上发现了黑色和黄色沉积物，主要是铜，铁和锰的氧化物（CuO，Cu（OH）2，Fe2O3，FeOOH和MnO2）。后续的台式实验表明，饮用水中的金属含量并不总是能预测塑料管表面的金属含量。pH 4的水导致大量金属释放到散装水中，而pH 7.5的水导致大量金属沉积在PEX管表面上。热水（55°C）会在pH 7.5的PEX管道表面上释放出大量有机物，并增加金属负载量。ATR-FTIR分析表明，在55°C时，连接到铜和黄铜组件的PEX管具有最大的氧化官能团峰强度（COOC，CO和COC）。这项研究强调了潜在的下游塑料管降解和金属沉积，这可能导致管道问题以及建筑物所有者，居民和自来水公司的故障。