CASE
STUDY
TURNING CYBER UNCERTAINTY INTO
A CLEAR ROADMAP FOR A MUNICIPAL WATER UTILITY
How a municipal water and wastewater operator gained a full view of its OT cybersecurity posture, established a structured improvement roadmap, and built the governance foundation needed to protect critical public infrastructure.
| Challenge | Solution | Result |
|---|---|---|
| No consolidated view of OT cybersecurity risk across water and wastewater operations | Structured OT cybersecurity assessment aligned to ISA/IEC 62443 across WTP, WWTP, and OT networks | Clear, documented understanding of OT cybersecurity posture and risk exposure |
| Architecture not aligned with ISA/IEC 62443 or Purdue Model principles | Qualitative risk analysis covering people, process, and technology domains | Actionable roadmap guiding governance, architecture, and operational improvements |
| Limited governance, monitoring capability, and OT-specific incident response | Phased risk treatment roadmap with prioritized actions across a 36-month horizon | Improved resilience of critical water and wastewater infrastructure |
Project Background
A municipal water utility responsible for water treatment and wastewater operations across a regional service area recognized that its OT environment required a structured cybersecurity review. With critical infrastructure obligations and increasing regulatory attention on industrial control system security, the organization needed an objective assessment of its current posture and a clear, standards-aligned path forward. The utility engaged Arista Cyber to conduct a comprehensive OT Cybersecurity Assessment covering its Water Treatment Plant, Wastewater Treatment Plant, OT networks, IT/OT interfaces, and cybersecurity processes across operations, maintenance, and IT functions.
Growing Cyber Risk, No Consolidated View, and a Need for Structured Direction
Municipal water utilities face a distinct cybersecurity challenge: the operational technology systems that control water treatment, distribution, and wastewater processing are safety-critical, continuously operating, and increasingly connected to broader IT environments. Yet many utilities have built their OT environments incrementally over many years, without the structured cybersecurity design that modern risk levels require.
This utility was no exception. Its existing OT architecture had not been evaluated against ISA/IEC 62443 or Purdue Model segmentation principles. Governance structures, OT-specific policies, and clearly defined cybersecurity roles had not been formally established. Visibility and monitoring capabilities across the OT environment were limited, making it difficult to detect anomalous activity or confirm the state of connected assets. Leadership had strong intent to address these issues but lacked the structured assessment and prioritized roadmap needed to direct effort and investment effectively.
The organization needed an objective, expert-led evaluation that could establish where it stood, where the most significant risks were concentrated, and what a credible improvement programme should look like, in a form that both technical teams and executive leadership could act on.
A Standards-Based Assessment Across People, Process, and Technology
Arista Cyber applied a structured, ISA/IEC 62443-aligned assessment methodology that evaluated the utility's OT cybersecurity posture across both technical and operational dimensions. The assessment approach was designed to produce findings that were specific, evidence-based, and directly actionable at each level of the organization.
The assessment covered:
Stakeholder Interviews Across IT, OT & Operations
Stakeholder interviews across IT, OT, and operational teams to establish a ground-truth view of actual security practices, not documented assumptions
Qualitative Risk Analysis Across People, Process & Technology
Qualitative risk analysis across people, process, and technology domains, identifying where risk was concentrated and what controls were most critically absent
Control Assessment Aligned to ISA/IEC 62443
Control assessment aligned to ISA/IEC 62443 requirements, establishing a gap profile against a recognised industry standard
OT Asset Discovery & Criticality Mapping
OT asset discovery and criticality mapping across the Water Treatment Plant and Wastewater Treatment Plant environments
Network Architecture Review Using Purdue Model
Network architecture review based on Purdue Model principles, evaluating segmentation, IT/OT separation, and remote access controls
Prioritization of Risks & Gaps for Resource Allocation
Identification and prioritization of risks and gaps to support resource allocation decisions
The assessment produced a structured set of deliverables for both technical teams and executive leadership, including a cybersecurity assessment report, asset inventory with risk ratings, a proposed segmented network architecture, a cybersecurity gap and risk heatmap, and an executive management summary.
A Documented Posture, a Phased Roadmap, and a Foundation for Long-Term Resilience
The engagement gave the utility's leadership and technical teams their first consolidated, objective view of OT cybersecurity risk across the entire operational environment. The assessment confirmed that while no extreme risks were present, the OT environment carried a moderate to high risk profile that required structured, prioritized action to reduce to a manageable level.
Arista Cyber developed a phased risk treatment roadmap structured across three implementation horizons, giving the organization a clear and sequenced path forward:
- Immediate actions (0 to 4 months): Establishing governance foundations and addressing the most critical access control and vulnerability gaps that carried the highest immediate risk exposure
- Short to medium term actions (up to 18 months): Implementing architecture segmentation improvements, enhancing monitoring capability, and advancing asset visibility and configuration management practices
- Long term actions (up to 36 months): Maturing the cybersecurity programme to full ISA/IEC 62443 alignment and implementing enterprise-wide security architecture and resilience capabilities
Beyond the roadmap, the engagement strengthened the utility's governance foundation by establishing a clear basis for OT cybersecurity policy development, role definition, and ongoing risk management. The executive summary provided leadership with the clarity needed to make informed investment decisions and communicate cybersecurity priorities across the organization.
The assessment positioned the utility to take a structured, evidence-based approach to improving the security and resilience of the water and wastewater infrastructure it is responsible for protecting, with a documented programme that could be measured, reported, and built upon over time.
Who Should Engage Arista Cyber?
IT and OT Leaders in industrial & critical infrastructure operations who want assurance, resilience, and measurable security outcomes.
What's The Next Step?
- Schedule a Cyber Risk Assessment
- Conduct an Executive Workshop
- Start OT Security Roadmap Planning
Operating critical water infrastructure? Contact Arista Cyber to assess your OT cybersecurity posture and build a roadmap that protects public safety and operational continuity.
