Hazard and operability reviews strengthen water and wastewater plant design

Water and wastewater treatment plants are designed to operate safely and reliably for decades. But even the best designs can contain hidden vulnerabilities that only become apparent during startup, operation, or unexpected conditions. Identifying those issues before construction begins can save time, reduce costs, and improve long-term reliability.

A recent article published in Journal AWWA, “Hazard and Operability Reviews Strengthen Water and Wastewater Plant Design,” explores how Hazard and Operability (HAZOP) reviews help utilities uncover potential risks early in the design process. Written by Carollo’s SJ Hall, Gregory Parana, Shawn Corrigan, and Milissa Hirst, the article highlights how this structured approach can strengthen safety, operability, and resilience across water infrastructure projects.

What Is a Hazard and Operability (HAZOP) Review?

A HAZOP review is a structured, team-based process used to identify potential hazards and operational challenges before a facility is built or modified. Originally developed for the chemical industry, HAZOP brings together engineers, operators, maintenance staff, and other specialists to systematically evaluate how a system could deviate from its intended operation.

As the authors explain, the process helps teams move beyond asking whether a system will work and instead ask, “What if something goes wrong?”

Improving Water and Wastewater Plant Design

Using tools such as piping and instrumentation diagrams (P&IDs), HAZOP teams evaluate scenarios like loss of flow, equipment failures, excessive pressure, or control system issues. Each potential deviation is examined for causes, consequences, existing safeguards, and opportunities for improvement.

The article shares an example in which a HAZOP review identified a risk that chemical metering pumps could continue operating at low tank levels, potentially damaging equipment. By adding a simple sensor and automatic shutdown control during design, the team reduced the risk of equipment failure and future maintenance issues.

Benefits Beyond Regulatory Compliance

While HAZOP reviews support regulatory and safety requirements, the authors emphasize that their value extends far beyond these requirements. Reviews often improve plant operability, strengthen documentation, support operator training, and provide a valuable record of design decisions for future staff.

The approach can also be adapted to emerging risks, including cybersecurity concerns, helping utilities evaluate vulnerabilities before they become operational problems.

A Proactive Approach to Risk Management for Water Utilities

The article concludes that HAZOP is more than a safety exercise. It is a practical tool for improving facility design, supporting reliable operations, and fostering a culture of proactive risk management.

Read the full article in Journal AWWA to learn how HAZOP reviews are helping utilities identify risks earlier, strengthen plant design, and build more resilient water and wastewater facilities.