Level of service assessment of drinking water systems : a decision support framework

Drinking water systems (DWSs) are infrastructure assets that are critical to public health, socio-economic resilience, and community overall wellness. In Canada, local governments are encountering mounting challenges in managing DWSs, such as outdated infrastructure, financial constraints, rapid population growth and urbanization, and the increasing impacts of climate change. Effective asset management of DWSs requires a clear understanding of assets, their operational functionality, and service performance, which is commonly evaluated through the Level of Service (LOS). LOS is one of the key concepts in asset management, which considers the specific factors and key performance indicators (KPIs) that define the quality of services delivered to the public. LOS serves as a foundation for decision making, as it guides local governments in prioritizing capital investments through targeted system improvements. This research developed a decision support framework for assessing LOS of DWSs through a sustainability lens. The framework is built around a structured model, which includes three methodological steps: (i) data collection, (ii) development of the overall LOS, and (iii) assessment of the LOS. The last step of the model was carried out at two levels. First, each system was assessed individually against target or acceptable LOS thresholds established for each KPI. Second, a comparative analysis was conducted using scenario-based analysis to reflect stakeholder priorities (neutral, pro-environment, pro-social, pro-economic). This dual approach enables both generating detailed system-level performance insights and identifying which system achieves the most balanced and sustainable outcomes across environmental, economic, and social dimensions. The developed model was applied to selected DWSs in British Columbia to demonstrate its relevance and utility. Three systems, two large drinking water systems (LDWSs) and one small drinking water system (SDWS), were studied using the proposed model. The findings highlight the necessity for tailored strategies to improve LOS in SDWS, which experience greater cost pressures, limited treatment capabilities, and an infrastructure deficit. This research will help decision makers evaluate LOS, identify weaknesses, and facilitate informed decision making in planning, operation & maintenance, and development of drinking water infrastructure.