Triple Top Line–Based Sustainability Measure for Water Distribution Systems

Abstract

To address the rapidly growing need for asset management of aging water distribution systems (WDS), this study introduces the adaptation of the triple top line (TTL) as a tool for WDS sustainability evaluation. The WDS TTL model is tested using EPANET hydraulic simulations of a hypothetical WDS subjected to multiple aging scenarios. The results of one aging scenario showed the sustainability index (SI) over the long term to be 0.52 for WDS with new pipe versus 0.23 for a WDS with old pipe, confirming the expectation of age influencing the SI. The testing showed pipe breakage rate to be the major contributing factor significantly decreasing economic sustainability. Additional analysis using the TTL model showed that replacing a pipe at an age of 70 years would maximize the sustainability measure of the WDS. Sensitivity analysis further illustrated that pipe aging, demand increase, water price reduction, and pipe breakage all acted to reduce sustainability, confirming the ability of the TTL model to provide useful insight into sustainability for planning, design, and operations comparative analyses.