Organic Leachates from Water Service Line Liners and Coatings and Their Fate in Drinking Water

Abstract

There is growing interest in using pipe lining and coating technologies to control corrosion and prevent release of metals (lead and copper) into drinking water from water service lines and from water pipes in homes, hospitals, hotels, and other buildings. Use of linings and coatings in small diameter pipes is expected to result in increased concentrations of any organic constituents able to leach into drinking water. Leaching of organic constituents from an epoxy coating and a polyethylene terephthalate (PET) liner, both potable water grade, was investigated using a fill-and-dump sampling technique employing long holding times to maximize the concentrations of leached constituents. Organic leachates of focus included bisphenols, bisphenol diglycidyl ethers (BDGEs), phthalic acids, and phthalate esters because these may pose endocrine disrupting risks when consumed. Analytical techniques included liquid chromatography/tandem mass spectrometry (MS), gas chromatography/MS, and time-of-flight MS. No phthalates were observed leaching from the PET liner; the epoxy coating leached low levels of bisphenol A (BPA), BPA-like compounds, and bisphenol A diglycidyl ether (BADGE). Assessing drinking water safety requires not only identifying leachates but also understanding their reactions in drinking water that may lead to by-products formation. Hydrolysis and chlorination reactions (with free chlorine and monochloramine) were investigated under drinking water conditions. Hydrolysis of BDGEs and chlorination of bisphenols were found to proceed at rates that may significantly influence human exposure to these compounds and their by-products in tap water. To facilitate future health risk assessments (by others), key by-products were identified and kinetic models of these reactions were developed. The BADGE hydrolysis model estimates residual BADGE concentrations from 15 to 40 °C and pH 2 to 12; half-lives at pH 7 and 15, 25, and 40°C were estimated to be 11, 4.6, and 1.4 days respectively. The chlorination (free chlorine) model estimates residual BPA and bisphenol F (BPF) concentrations from 15 to 25 °C and pH 3 to 12, with estimated BPA and BPF half-lives (with 1 mg/L of free chlorine, pH 6 to 11, and 10 to 25 °C) estimated to be from 3 to 35 min.