Environmental impact assessment of digital water meters throughout urban water cycle

Utilizing digital measurement devices enhances the efficiency and reliability of urban water systems. For instance, digital water meters (DWMs) measure high-resolution water consumption at customer sites, serving both personal awareness raising and advanced water loss management in water distribution networks (WDNs). However, the pros and cons of these devices in terms of environmental impacts have yet to be fully unrevealed. This research aims to bridge this gap by conducting a comprehensive environmental assessment focused on the implementation of DWMs. The assessment considers not only the direct environmental impact of DWMs (e.g., due to production, installation, etc.) but also their indirect effects on the entire urban water cycle due to their usage. As an example of an indirect effect, using DWMs can reduce household water demand by promoting awareness. This leads to less freshwater treatment and pumping, decreased hot water and energy consumption in households, and a lower volume of wastewater generation. Thus, the current study categorizes the indirect effects on the urban water cycle into three scales: freshwater scale (including freshwater treatment and pumping energy), water user scale (involving energy consumption for water heating), and wastewater scale (including wastewater treatment).

Life cycle assessment (LCA) is used as a holistic approach to quantify environmental impacts. Accordingly, the system boundary is defined to encompass the entire life cycle of DWMs (from production to end-of-life), as well as the three scales reflecting indirect effects. An Alpine city in Austria with 105,000 inhabitants is selected as a case study, where the impacts of deploying DWMs are evaluated by defining three scenarios according to the requirements of the study area. These scenarios include: (1) Reducing 5% of total leakage, (2) Reducing 15% of water demand, and (3) combining (1) and (2). For each scenario, comprehensive datasets on resources, processes, and energy consumption are compiled, and impacts are quantified using the LCA software SimaPro 9.0.

Evaluating the environmental impacts of the study area in the existing situation (i.e., without any DWMs) shows that the water user scale (including energy for water heating) contributes to 80% of the total impacts. Thus, applying the second and third scenarios results in substantial energy savings across all scales (particularly water users) compared to the existing situation, reducing the environmental impacts ranging from 3 to 4 million kilograms of CO2 equivalent per year. This fluctuation is tied to the lifespan of the DWMs, extending from 2 to 8 years.

The proposed framework can explore the extent to which DWM deployment is sustainable, providing a blueprint for decision-makers to assess the effectiveness of similar interventions in different urban settings.