How Drift Affects Regulatory Compliance and Public Safety

Cooling Tower Drift

Introduction: Cooling towers are essential for thermal management in industrial plants, data centers, and power facilities. However, one often-overlooked byproduct of cooling tower operation is drift—tiny water droplets that escape with exhaust air. These droplets can carry chemicals, microbes, and other harmful substances into the surrounding environment, creating risks for public health, regulatory violations, and reputational damage. In this article, we explain what drift is, why it matters, and how modern solutions can help mitigate the problem.

1. What is Cooling Tower Drift? Drift refers to small water droplets that become entrained in the airflow exiting a cooling tower. Unlike evaporation—which is a desired part of the cooling process—drift involves actual liquid water that escapes from the system.

These droplets can contain:

• Chemicals used in water treatment (e.g., biocides, corrosion inhibitors, scale reducers)

• Microorganisms, including Legionella bacteria

• Minerals and solids, contributing to particulate matter (PM10, PM2.5)

Drift typically occurs when airflow passes through the tower’s mist without effective droplet separation. While most systems include drift eliminators, their efficiency can degrade over time or under high airflow conditions, allowing droplets to escape.

2. Regulatory Risks Uncontrolled drift can expose operators to a variety of regulatory issues:

• Air Quality Regulations: Drift droplets can contribute to local air pollution, especially if they contain dissolved solids or treatment chemicals. This is particularly relevant in areas with strict PM10 or volatile organic compound (VOC) limits.

• Water Treatment Compliance: Many facilities must report and control chemical discharge—not only to water but to air. Drift bypasses traditional discharge pathways and may result in unmonitored environmental release.

• Legionella Prevention: Guidelines such as ASHRAE Standard 188 and CDC regulations require strict monitoring and prevention of Legionella bacteria in cooling systems. Drift increases the potential for airborne transmission, which can lead to Legionnaires’ disease outbreaks.

• Permitting Issues: Local environmental agencies may impose operating limits or require mitigation strategies for facilities producing visible or harmful drift.

  
  

3. Public Safety Concerns Even when legal limits are not exceeded, drift can create public safety and reputational risks:

• Human Exposure: Drift can settle on nearby sidewalks, parking lots, or public spaces, where humans may inhale or come into contact with contaminants.

• Agricultural Impact: In rural areas, drift may fall on crops, affecting water-sensitive agriculture or introducing unwanted chemicals to the food chain.

• Infrastructure Damage: Over time, high mineral content in drift can corrode nearby structures, vehicles, or equipment.

• Legal Liability: Facilities that fail to manage drift effectively may face lawsuits or enforcement actions, especially if there’s evidence of illness or environmental degradation.

  
  

4. Technologies for Drift Reduction The good news is that drift can be controlled with modern solutions:

• High-Efficiency Drift Eliminators: These are mechanical devices placed at the top of the tower fill area to capture droplets before they exit the tower. Advanced designs can reduce drift loss to below 0.0005% of the circulating water flow.

• Real-Time Monitoring: Solutions like Infinite Cooling’s TowerPulse™ provide continuous visibility into fan performance, fill condition, and operating parameters, helping detect abnormal drift events before they become serious.

• Plume Capture Technology: While designed for plume abatement and water recovery, technologies like WaterPanel™ also reduce the physical emission of drift by capturing condensate at the tower exhaust, effectively minimizing both visible and invisible emissions.

  
  

5. Case Studies & Best Practices At a Midwestern chemical plant, installation of high-efficiency drift eliminators and TowerPulse™ reduced measured drift by over 90%, bringing emissions well below local PM10 thresholds.

In another case, a power facility in a water-stressed region leveraged WaterPanel™ to cut visible plume and drift, addressing both environmental and community concerns in a single retrofit.

Conclusion: Controlling drift is no longer optional—it’s a critical part of regulatory compliance, public safety, and sustainable industrial operations. With solutions like high-efficiency drift eliminators, smart monitoring, and plume capture technologies, facilities can proactively manage risk and ensure long-term operational success.

Keywords: cooling tower drift, drift eliminators, Legionella cooling tower, ASHRAE 188 compliance, industrial air emissions, plume control