Both status and progress in smart water metering (SWM) implementations in five selected countries (i.e., United States of America, United Kingdom, Australia, Israel, and South Korea) are investigated in this study. Despite the countless benefits of SWM implementation, the diffusion of the SWM technologies has been slow due to various challenges, including the absence of compulsory water policies, the lack of support from customers and expertise, and weak cost–benefit analysis. Over the past 30 years, the aforementioned countries have transitioned from a fixed charging to a volumetric charging regime composed of traditional water meters and SWM. Both the status and progress of SWM implementation are quite different among countries, although governments across the world have been applying water policies responding to water scarcity, population growth, and water demand management. However, the absence of strong water policies and political support for SWM implementation resulted in the slow and retarded spread of SWM implementation. Although several changes in water policies have occurred since 1990, there is no compulsory law for SWM implementation. Between 1995 and 2010, pilot/trial cases for SWM were dominant. After 2010, the number of SWM implementation kept increasing and all countries experienced more concentrated SWM implementation, despite the variances in both endpoints and completion of SWM implementation depending on water policies (i.e., acts and regulations) encouraging SWM implementations. The global market for SWM has consistently grown to USD 5.92 billion in 2020. Finally, the application of favourable water policies to optimize the use of water resources and to promote sustainable development is expected to drive the SWM market further.

This study investigates the water–energy–carbon (WEC) nexus in cities across four countries, namely the United Kingdom (UK), the United States of America (USA), Australia (AUS), and South Korea (KOR), over a decade, from 2011 to 2021. The primary objective is to assess the impact of smart water metering (SWM) implementation on the WEC nexus, with a specific focus on domestic hot water (DHW) consumption and associated greenhouse gas (GHG) emissions. The analysis of the collected data reveals diverse patterns among cities with varying levels of SWM implementation. Notably, cities with higher SWM implementation demonstrated significant reductions in water consumption, indicating the effectiveness of the efficient water consumption and demand management achieved through SWM. The study emphasizes the importance of addressing GHG emissions related to water heating, with the carbon intensity of water heating identified as a critical factor in this context. To achieve net reductions in GHG emissions, intensive efforts are required to simultaneously decrease both DHW consumption and the carbon intensity of water heating. The research findings highlight the potential for substantial GHG emissions reductions by combining SWM implementation with the decarbonization of water heating. By recognizing the interdependencies within WEC systems, this study underscores the significance of SWM in advancing toward a carbon-neutral society. In conclusion, this study contributes valuable insights into the WEC nexus and emphasizes the role of SWM in achieving sustainability goals. It advocates for integrated policies to effectively address the interconnected issues of the WEC nexus for effective climate change mitigation.