Decarbonization Strategy Best Practices Derived from a Water Utility Experience Survey

Water utilities are experiencing climate change impacts such as flooding, energy disruptions, and extreme temperatures, alongside existing challenges of serving growing populations, aging infrastructure, and meeting evolving regulations under budget constraints. Despite these challenges, the water sector holds potential to both reduce greenhouse gas (GHG) emissions and build resiliency to climate impacts. Water utilities are increasingly adopting decarbonization strategies, but face challenges due to limited guidance, technical uncertainties, and resource constraints. To characterize current practices, barriers, and opportunities in decarbonization strategy development and implementation, we surveyed 28 water utilities across six countries. The survey explored key components of decarbonization strategies, including GHG emission inventorying, monitoring of fugitive emissions (notably nitrous oxide [N[sub]2[/sub]O] and methane [CH[sub]4[/sub>), mitigation methods, climate adaptation and resiliency, and the challenges and opportunities utilities experienced in implementing these strategies.

Key survey insights include:
• Figure 1 summarizes the key components that utilities included in their decarbonization strategies. Seventy-nine percent of the utilities have adopted climate action plans, most of which were created in the past five years, indicating rapid sectoral progress.
• Figure 2 shows the GHG emission sources utilities included in their GHG emission inventories. Over 90% of the utilities maintain emission inventories, with most including scope 1 and 2 sources.
• Table 1 shows the GHG emissions utilities are measuring, and the measurement locations. Fifty-seven percent of the utilities measure N[sub]2[/sub]O, CH[sub]4[/sub], and/or CO[sub]2[/sub].
• Figures 3, 4, and 5, show the mitigation methods utilities are implementing to reduce emissions from energy-use, N[sub]2[/sub]O, and CH[sub]4[/sub], respectively. All of the utilities are reducing energy-related emissions, 80% are addressing N[sub]2[/sub]O, and 90% are addressing CH[sub]4[/sub].
• Figure 6 summarizes the challenges utilities experienced in creating and implementing decarbonization strategies.

Most challenges were related to technical and financial constraints, whereas leadership and strategic priorities were the main drivers of GHG reduction activities. The survey found that while most utilities have made significant advances in reporting and reducing energy-related emissions, many struggle with monitoring and mitigation process emissions of N[sub]2[/sub]O and CH[sub]4[/sub], which are often the largest contributors to wastewater sector emissions. The lack of a structured, step-by-step approach can result in focusing on less significant emission sources, resulting in slower progress and higher costs, underscoring the need for a practical framework they can follow. Drawing from these findings, and experiences using these findings to develop a strategy for a Municipality in Ontario (whose strategy was presented at WEFTEC 2025), the authors developed the Water Utility Net-Zero Strategy Best Practice Framework. This framework is a systematic, four-phase guide designed to help utilities create, assess and continuously improve their decarbonization strategies. Shown in Figure 7, the framework provides guidance on the following phases:

• [b]Phase 1: Evaluate[/b] the utility's existing goals and commitments, services, climate risks, and GHG emission impact through annual GHG emission inventories that include Scope 1, 2, and 3 emissions.
• [b]Phase 2: Plan[/b] cost-effective and feasible GHG mitigation projects and prioritize each using utility-defined criteria. Develop a roadmap outlining implementation methods, timelines, and expected reductions.
• [b]Phase 3: Implement[/b] the roadmap, refining mitigation methods during design. Monitor progress annually though updated GHG inventories, comparing actual reductions to projected targets.
• [b]Phase 4: Rework and Refine[/b] the strategy to reflect new industry knowledge, evolving technology, and experiences (i.e., implementing mitigations, or measuring GHGs) and challenges encountered in meeting reduction goals. To supplement the framework, the authors created a Best Practice Checklist Tool, enabling utilities to self-evaluate the maturity of their strategy compared against each step of the framework, and identify actionable improvements. Screen captures from this tool are shown in Figures 8 and 9. This work is among the first to consolidate global experiences into actionable guidance for water utilities worldwide. The findings provide an overview of the current state of water utility decarbonization strategy advancements informed by global experiences and synthesizes this knowledge into practical guidance and tools. The framework and checklist tool are designed for broad applicability, enabling utilities of vary sizes, capacities, and that reside in varying jurisdictions, to systematically advance their GHG reduction commitments, while mitigating risks through informed, strategic decision-making.