Life-cycle assessment of common water main materials in water distribution networks

This paper examines the economy-wide environmental impacts linked to the manufacturing of PVC and ductile iron (DI) pipes, steel tanks, and to the generation of electricity for pumping in water distribution network optimization. The non-dominated sorting genetic algorithm (NSGA-II) is used to generate Pareto-optimal solutions of the benchmark ‘Anytown’ network expansion problem. Selected Pareto-optimal solutions of the ‘Anytown’ network are evaluated with an economic input–output life-cycle assessment (EIO-LCA) and 14 environmental measures on air emissions, non-renewable energy use and environmental releases. The major findings suggest that DI and PVC pipe manufacturing and electricity generation activities (for pumping) have higher environmental impacts than steel tank manufacturing and construction activities in the ‘Anytown’ network. The EIO-LCA suggests that DI pipe manufacturing is linked to: (i) carbon monoxide emissions from truck transportation and wholesale trade and (ii) land and underground toxic releases from metal mining activities. PVC pipe manufacturing is linked to: (i) carbon monoxide emissions from truck transportation, (ii) toxic air releases from the plastics material and resin manufacturing sector, (iii) land and underground toxic releases from metal mining and resin manufacturing, and (iv) natural gas use for plastics material and resin manufacturing.