In November 2025, a chiller plant failure at a CyrusOne facility near Chicago shut down CME Group's derivatives exchange for nearly ten hours, freezing billions of dollars in transactions. The cause wasn't a cyberattack or a software glitch. Reports indicated the issue stemmed from a mechanical cooling failure. Inside the facility, temperatures soared past 100°F despite frigid weather outside, triggering automatic shutdowns to protect equipment.

That incident made headlines, but the underlying dynamic is common across the industry. Uptime Institute's outage research has consistently found that power and cooling issues are the leading causes of significant data center outages — with power alone responsible for 54% of impactful outages in 2024 and cooling the second most common cause. And as AI workloads push rack densities higher and thermal margins tighter, the cooling systems keeping those servers alive are under more pressure than ever.

The question most facility teams should be asking isn't whether their cooling will hold up during normal operations. It's whether their water treatment program is designed to prevent the slow, invisible failures that erode cooling performance long before anything trips an alarm.

What Role Do Cooling Towers Play in Data Center Failures?

Cooling towers are the workhorses of data center thermal management. They remove heat from the chilled water loops that keep servers, storage systems, and network hardware at safe operating temperatures. When a cooling tower fails to operate efficiently, the entire cooling infrastructure is compromised — chillers work harder, energy consumption spikes, and the facility moves closer to the thermal thresholds that trigger automatic server shutdowns.

But cooling towers don't typically fail all at once. They degrade. And in most cases, the degradation begins with what's happening inside the water itself.

What Actually Causes Cooling System Failures?

When a water treatment specialist walks into a data center cooling tower that's underperforming, they aren't looking at the mechanical components first. They're looking for visual signs of scale buildup, corrosion, and microbiological deposits like biofilms or slime. The presence of any of these tells them immediately that heat transfer efficiency is degraded and that the current chemical program is either incorrectly dosed or failing to penetrate the system properly.

These three failure modes — scaling, corrosion, and biofouling — are the primary culprits behind the vast majority of cooling system problems in data centers.

And they rarely show up in isolation. They reinforce each other in what water treatment professionals call the corrosion-deposition-biofouling triangle: scale deposits create low-flow zones where biological growth thrives, biofilm traps corrosion byproducts against metal surfaces, and corrosion products become nucleation sites for additional scale.

Managing any one of these without addressing the other two is a losing strategy.

How Does Scale Affect Cooling Tower Efficiency?

Scale forms when dissolved solids — primarily calcium, magnesium, and silica — precipitate out of the water and deposit on heat transfer surfaces. As water evaporates in a cooling tower, those minerals concentrate. At high enough saturation levels, they crystallize and adhere to the interior surfaces of heat exchangers, condensers, and piping.

The effect is immediate and measurable. Scale acts as a thermal insulator, and even a thin layer has a disproportionate impact on system performance. Even a thin layer of scale can reduce efficiency by 5-10%, with heavier buildup driving losses well beyond 20%. In a data center running at high rack densities where every degree of cooling efficiency matters, those losses translate directly into higher operating costs, reduced cooling capacity, and a shrinking margin between "the system is holding" and "servers are throttling."

Scale also forces the system to perform more frequent blowdowns — ejecting water to reduce mineral concentration — which wastes significant volumes of water, often amounting to hundreds of thousands or even millions of gallons annually in large facilities, and drives up sewer costs. For facilities under corporate mandates to reduce water usage, this creates a direct conflict between system protection and sustainability targets.

Can Bacteria Cause Cooling Failures in Data Centers?

Yes, and they do it more often than most facility teams realize. Cooling towers are open systems, constantly pulling in ambient air along with dust, pollen, and airborne microorganisms. The warm, nutrient-rich water inside the tower provides an ideal environment for bacterial growth, algae, and biofilm formation.

Biofilm is particularly damaging because it adheres directly to internal surfaces and creates an insulating layer that is even more thermally resistant than mineral scale. Facilities often blame mechanical failures for efficiency drops, but the root cause is frequently undetected biofilm that traditional chemical doses can't penetrate. Once biofilm establishes itself, it also induces further localized corrosion and scaling beneath the deposit — compounding the damage in ways that aren't visible until performance has already degraded significantly.

Left unchecked, these biological environments can also harbor dangerous waterborne pathogens like Legionella, creating severe health, safety, and compliance liabilities that go well beyond equipment performance. For data centers in densely populated areas, a Legionella incident can trigger regulatory action, public health investigations, and the kind of reputational damage that no amount of uptime can offset.

The speed of impact surprises most operators. Biofilm and scale can severely affect a system in a matter of days or weeks — not months. Conversely, when proper treatment is applied, the turnaround can be equally fast. Effective biocidal chemistry can visibly improve water clarity and destroy existing slime within a single week.

Are Traditional Water Treatment Chemicals Causing Problems in Data Centers?

Most conventional cooling water programs rely on petroleum-based chemicals and bulk hazardous materials like liquid bleach for biological control.

These programs were designed for an era when the primary concern was keeping the tower clean, and the approach was straightforward: dose heavily, blow down frequently, and send a technician out once a quarter to check the numbers.

Data centers face a different reality.

Traditional bulk bleach deliveries create significant transportation, storage, and handling safety risks — particularly for facilities in densely populated areas where a chemical spill or exposure incident carries regulatory and liability consequences. The fumes alone create workplace safety concerns that many facility teams simply accept as a cost of doing business.

Beyond the safety dimension, conventional treatments often actively hinder data centers from meeting their sustainability and water conservation goals. High blowdown rates conflict with water reduction KPIs. Phosphate- and zinc-based corrosion inhibitors face increasing discharge restrictions in multiple jurisdictions. And the "set it and forget it" approach that characterizes many generic vendor programs leads to what experienced water treatment professionals call the original sin of the industry: running out of chemical completely.

Without someone actively managing inventory and adjusting dosing to match changing system loads, tanks run dry and critical infrastructure goes unprotected — sometimes for days before anyone notices.

What Happens When Data Center Cooling Water Treatment Fails?

The effects cascade, starting with a drop in heat transfer efficiency that shows up as higher energy consumption and rising operating costs. The system compensates by working harder — chillers draw more power, pumps run at higher speeds, and blowdown frequency increases to manage water quality that's already deteriorating.

As the degradation continues, equipment stress accumulates. Heat exchanger components, pumps, and fans operating under persistent thermal load wear faster than designed. Corrosion weakens piping and structural components. Pitting corrosion creates localized failures — a pinhole leak in a chilled water loop can damage surrounding IT infrastructure before the source is identified.

The endpoint is unplanned downtime. According to the ITIC 2024 Hourly Cost of Downtime Survey, over 90% of mid-size and large enterprises report that a single hour of downtime exceeds $300,000, with 41% reporting costs of $1 million or more per hour. Facility managers describe these incidents in plain terms: career-ending events.

None of this is inevitable.

The water chemistry problems that lead to cooling failures develop over weeks and months, not overnight. A program designed to catch them early prevents the cascade entirely. A reactive program catches them when the chiller plant is already struggling to hold setpoint.

How Can Data Centers Prevent Cooling Tower Failures?

Prevention starts with a fundamental shift: treating water management as a continuous, data-driven discipline rather than a quarterly chemical delivery.

Continuous remote monitoring is the foundation. Systems that track critical parameters like pH, conductivity, and chemical residuals in real time — 24 hours a day, 7 days a week — catch the problems that scheduled manual testing misses entirely. A sudden spike in conductivity, a pump failure, a chemical feed interruption: continuous monitoring triggers an immediate alarm via email or text, turning what would have been an undetected overnight failure into a correctable event. VeriTrac, CRB Water's remote monitoring platform, provides this kind of real-time oversight, giving facility teams and their water treatment partner visibility into system performance around the clock.

On the chemistry side, newer approaches are closing the gap between environmental goals and system protection. On-site chemical generation eliminates the hazard, logistics, and carbon footprint of bulk chemical delivery. MIOX systems generate a highly effective mixed oxidant disinfectant on-site using only salt, water, and electricity, replacing bulk bleach entirely.

Facility staff handle safe bags of salt instead of hazardous liquid chemicals, acid feed requirements drop significantly, and the biocidal efficacy is strong enough to reduce existing biofilm and improve system cleanliness.

For scale and biological inhibition, plant-based treatment chemistries offer a path that conventional petroleum-based programs can't match. ProMoss provides natural scale and biofilm inhibition, while EnviroTrac plant-based inhibitors deliver corrosion protection without the environmental concerns tied to traditional phosphate and zinc formulations.

These programs represent a fundamentally different approach to cooling water management that aligns with the sustainability KPIs data centers are increasingly measured against.

But chemistry and monitoring alone aren't enough without the right people behind them.

The difference between a facility that thinks it has a good water treatment program and one that actually does comes down to the relationship between the facility team and their water treatment partner. Generic vendors drop off chemicals and wait for the facility to report a failure.

A genuine partner — one with tenured technical reps who understand both the water chemistry and the operational reality of a mission-critical facility — continuously optimizes the system, manages chemical inventory proactively, and responds in hours rather than days when something shifts.

What Should a Facility Manager Do First?

Data center operators who want to evaluate their current program should start with a comprehensive technical plant audit from a water treatment specialist — not a sales call, but a systematic assessment of what's actually happening in the system.

Before that conversation, it helps to have a few things ready: current utility usage and costs, an accurate water balance showing water in versus water out, and block flow diagrams of the existing cooling systems. That baseline allows a specialist to identify where the gaps are and quantify the operational and financial exposure the facility is currently carrying.

The water chemistry problems behind cooling failures are preventable. They just require a program designed for the thermal loads, uptime requirements, and sustainability constraints specific to mission-critical cooling — not a generic commercial HVAC recipe applied to a facility where the stakes are orders of magnitude higher.

If you're responsible for cooling system reliability at a data center and want to understand where your current water treatment program stands, request a cooling system risk assessment today. Our experts can walk through your system and identify hidden inefficiencies, water chemistry risks, and operation gaps before they become a problem.