I would certainly agree with the authors of this paper that the existing metrics that have been applied to sustainability assessments of water services are not very good. In some cases the metrics are unproven. But I would go further to say that considering several flawed metrics together does not necessarily result in a better decision compared to using only one metric. In fact, several metrics could lead one even further astray, wandering in the dark with a faulty flashlight. Applying common sense and traditional metrics will get us further faster.
Xue X, Schoen ME, Ma XC, Hawkins TR, Ashbolt NJ, Cashdollar J, Garland J. Critical insights for a sustainability framework to address integrated community water services: Technical metrics and approaches. Water Research. 2015 Mar 25;77:155-169. doi: 10.1016/j.watres.2015.03.017.
Planning for sustainable community water systems requires a comprehensive understanding and assessment of the integrated source-drinking-wastewater systems over their life-cycles. Although traditional life cycle assessment and similar tools (e.g. footprints and emergy) have been applied to elements of these water services (i.e. water resources, drinking water, stormwater or wastewater treatment alone), we argue for the importance of developing and combining the system-based tools and metrics in order to holistically evaluate the complete water service system based on the concept of integrated resource management. We analyzed the strengths and weaknesses of key system-based tools and metrics, and discuss future directions to identify more sustainable municipal water services. Such efforts may include the need for novel metrics that address system adaptability to future changes and infrastructure robustness. Caution is also necessary when coupling fundamentally different tools so to avoid misunderstanding and consequently misleading decision-making.
Paper is here (fee).