Water and wastewater resilience: are your OT controls keeping up?

TL;DR: Water and wastewater utilities face rising cyber risk because IT/OT convergence expands the attack surface, internet-exposed devices and weak remote access remain common, and less than 25% of U.S. utilities undergo an annual cyber risk assessment, according to Nozomi Networks. OT resilience now depends on visibility, dynamic risk prioritisation and response readiness, not patching alone.

Editorial analysis by NHI Mgmt Group, based on content published by Nozomi Networks: “How to Strengthen Cybersecurity Resilience for Public Water and Wastewater Utilities”.

By the numbers:

• Less than 25% of water and wastewater utilities in the U.S. undergo an annual cyber risk assessment, according to Nozomi Networks.
• Water and wastewater utilities are one of 16 critical national infrastructure segments, according to Nozomi Networks.

Key questions

Q: What breaks in OT environments when utilities rely on static asset lists and institutional knowledge?

A: Security teams lose the ability to prioritise risk against current exposure.

Q: Why do weak segmentation and insecure remote access increase risk in water utilities?

A: They collapse the boundary between ordinary administrative connectivity and control-system access.

Q: How should water utilities prioritise OT remediation when patching is limited?

A: Prioritise by exploitability, exposure, asset criticality and process impact rather than by vulnerability count alone.

Practitioner guidance

• Build a real-time OT asset inventory Track every connected device, protocol and remote path across plants, stations and field sites so exposure is visible before prioritisation starts.
• Baselining normal communications Use passive monitoring to establish normal traffic, then flag new services, unusual protocols and unexpected remote connections for review.
• Prioritise remediation by operational impact Rank vulnerabilities by exploitability, exposure and process criticality, and move unsupported assets, default credentials and internet-facing services to the top of the queue.

Bottom line: Water and wastewater utilities face a compounded risk model because connectivity expands access paths while operational constraints limit conventional patching.

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