Water supply infrastructures are essential to ensure the well-being of communities and to support social and economic growth and must be protected from damage in the context of future threats related to the environmental consequences of climate change. Those consequences include natural disasters, i.e., landslides, which can cause destruction of water infrastructure, causing distress for water users, cascading effects to other critical infrastructures and environmental impacts. Vulnerability analyses represent a key point in international risk management programs for protecting critical infrastructure, especially in the context of climate change. In this paper, a methodology is proposed to evaluate crucial water supply infrastructure vulnerabilities based on multiple indicators. A learning-from-experience approach is applied to establish specific indicators for vulnerability assessment. Eight different indicators are identified, divided into four categories, regarding land characteristics, service inefficiencies for users due to infrastructure failure, pipeline route characteristics, and physical characteristics of the aqueduct pipe. Along with the indicators, a graphical representation is proposed using the Kiviat chart, producing a vulnerability chart that represents a useful tool to identify the main vulnerability factors in existing water supply infrastructure, in the management of interventions and in the planning and design processes of new infrastructure and for comparing different design solutions.