Unlocking energy-carbon-water synergies in global water supply system maintenance

Drinking water system maintenance faces rising energy, carbon, and water pressures, but integrated optimization strategies remain limited. Here we developed an energy-carbon-water nexus framework to quantify the resource efficiency gains of replacing conventional unidirectional flushing with air scouring, ice pigging, and their combined use across pipe, city, and regional scales. At the pipe scale, air scouring and ice pigging reduced energy use by 12%-68%, carbon footprint by 7%-84%, and water use by 56%-91% relative to unidirectional flushing. When scaled to 258,000 km of pipelines across 50 cities and regions, emerging technologies reduced annual energy use by 4.40×10⁷-4.80×10⁷ kWh, carbon emissions by 2.26×10⁸-7.56×10⁸kg CO₂, and water use by 4.12×10⁷-6.12×10⁷ m³. Prioritizing large-diameter pipes yielded resource and economic cost savings equivalent to 4-19 years of unidirectional flushing over a 30-year transition. These findings reveal substantial opportunities to improve resource efficiency in water infrastructure maintenance and advance sustainable urban water systems.