When water safety is compromised: preparing for cyberattacks on purification systems

When water safety is compromised: preparing for cyberattacks on purification systems

It starts at the source.A technician notices strange readings in the chemical dosage panel. Automated alerts begin to stack up. Chlorine levels spike outside acceptable limits. Minutes later, the flow of clean water halts entirely. It takes hours before the cause becomes clear: external access to the treatment control system, intentionally manipulated.

This is not a theoretical risk. Across Europe, water utilities are increasingly aware of their exposure. Water treatment facilities often run on legacy operational technology (OT) systems—built for reliability, not for resilience. The threat is no longer "if", but "when".

A fragile balance

Modern water systems rely on precision. Chemical levels, pressure, flow, and timing must be balanced in real time. When threat actors access the OT layer, they don’t just disrupt the process. They compromise public health.

An undetected change in chemical dosing can lead to under-treatment, allowing bacteria or contaminants to enter the supply. Overdosing creates its own risks, affecting water quality and safety. Even short-term disruption undermines trust in a service the public depends on without question.

When people hesitate to drink from the tap, the impact goes far beyond infrastructure. It becomes a societal breach.

Why the risk is growing

As water systems become more connected, the attack surface expands. Remote access tools, sensor-based automation, and cloud-connected dashboards improve efficiency, but also increase exposure.

Few facilities combine IT and OT security under one roof. Fewer still run crisis simulations that involve both technical teams and public-facing leadership. And many remain unaware of just how visible their systems are to external scanning tools.

Meanwhile, threat actors are increasingly looking at utilities not just for disruption, but as symbolic targets: if you can affect the water, you can affect the nation.

What resilience really looks like

It’s not just about protecting pumps and panels. It’s about being ready to respond when something slips through. True resilience in the water sector begins with clearly defined thresholds and alerts, parameters that flag unusual chemical dosing patterns before they become a risk. These early warnings give teams time to act before the public is affected.

Resilience also means having operational protocols in place to isolate contaminated supply quickly and safely. When a threat is detected, action must follow immediately, without ambiguity or delay.

In addition, it requires strong coordination between cybersecurity experts, plant operators, and those responsible for public communication. Everyone must know their role, and how decisions flow between teams.

And finally, resilience depends on having a trusted, secure communication channel that allows leadership to inform stakeholders calmly and clearly, even when systems are compromised.

Most importantly, it means acknowledging that water security is also reputational security. The public must believe the system works, even when something goes wrong.

Turning awareness into readiness

If a cyberattack hit your purification system tomorrow, would you know how to separate threat from accident? Could you coordinate a safe shutdown and communicate clearly with the public? Would you be able to reassure regulators, health authorities, and citizens?

A few hours of inaction or silence in the face of uncertainty can do lasting damage.

Let’s talk about how to build operational trust, so that when systems are challenged, the people who rely on them still can be too.