Drinking water distribution system is required to transfer water from the treatment plants to consumers. Polyvinyl chloride (PVC) pipes and high-density polyethylene (HDPE) pipes are commonly used plastic pipes for potable water transportation. This study attempts to conduct a life cycle assessment to compare the environmental impact of the two pipe materials over a period of 50 years. In addition, the effect of carbon content of different polymers was evaluated. Pipes of 1 Km length and 200 mm nominal diameter were considered. HDPE showed higher impact on the global warming potential at the production stage. The PVC polymer and HDPE polymer caused the highest impact, followed by pipe extrusion process and electricity. HDPE pipe also showed the highest impact on the whole life cycle. Pumping electricity consumption was calculated to be less for PVC of 0.38 GWh compared to 0.49 GWh for HDPE. The higher pumping electricity for HDPE pipe is not only due to its slightly lower Hazen-William’s roughness coefficient, but it is mainly attributed to its lower tensile strength which requires thicker pipe wall and hence smaller pipe hydraulic diameter. Accordingly, our study showed that PVC has higher advantage regarding its impact on global warming potential. In addition, PVC has less carbon content compared to other commonly used plastic pipes such as HDPE. For example, by using 1000 tons of fossil carbon, 259 Km and 656 Km HDPE and PVC pipes, respectively, can be produced. Accordingly, the risk induced on fossil resource scarcity was shown to be 1.5 times higher for the 1 Km HDPE pipe compared to the PVC pipe.
Al-Mallahi et al. (Thu,) studied this question.