A dirty cooling tower isn’t just an aesthetic problem — it’s a performance problem, a compliance risk, and often a hidden source of unnecessary water waste. If your facility hasn’t established a regular cleaning schedule, you’re likely spending more on water, chemicals, and energy than you need to.
The Short Answer
Most cooling tower experts recommend a thorough cleaning at least twice per year — once before the cooling season begins and once after it ends. For towers that operate year-round in warm climates, quarterly cleaning is the standard recommendation. Buildings in areas with heavy airborne debris (construction zones, agricultural areas, or high-pollen environments) may need even more frequent attention.
The U.S. Department of Energy’s Best Management Practice 10 emphasizes that regular tower cleaning is fundamental to maintaining both water efficiency and cooling performance. A tower operating with fouled fill, scaled heat exchange surfaces, or a debris-laden basin works harder and wastes more water than a clean one.
What Happens When You Skip Cleaning
When a cooling tower goes too long without cleaning, several problems compound. Scale buildup on fill media and heat exchange surfaces reduces the tower’s thermal efficiency, forcing it to work harder — which means more fan energy and more water consumption. Biological growth, including algae in sun-exposed areas and biofilm on submerged surfaces, reduces water flow through the fill and creates health risks. Sediment accumulation in the basin provides a nutrient-rich environment for bacteria, including Legionella, and can clog blowdown valves and strainers.
The water waste connection is direct. A scaled cooling tower can use 10 to 20 percent more water than a clean one operating at the same heat load. For a tower consuming 100,000 gallons per month, that’s 10,000 to 20,000 gallons of unnecessary water consumption — water you’re paying for twice (once as water, once as sewer charges). If you’re already receiving sewer credits, a dirty tower is reducing the efficiency of those credits by increasing your total water consumption relative to your cooling output.
What a Thorough Cleaning Includes
A proper cooling tower cleaning goes beyond hosing off the visible surfaces. It includes draining the basin completely and removing accumulated sediment, pressure washing the fill media to remove scale and biological growth, inspecting and cleaning the distribution deck and nozzles, cleaning or replacing drift eliminators, inspecting the basin coating for cracks or deterioration, flushing all blowdown and makeup water piping, and a fresh application of chemical treatment before refilling.
This is also the right time to inspect submeters and monitoring equipment. If your facility uses submeters for sewer credit documentation, verify that the meters are reading accurately during the cleaning shutdown. A meter that has drifted out of calibration will produce inaccurate data for your credit renewal.
Cleaning and Legionella Compliance
Cooling tower cleaning is a core requirement of any Legionella water management plan. The CDC’s guidance on Legionella water management specifically calls out cooling tower maintenance as a critical control point. ASHRAE Standard 188, which many jurisdictions now mandate, requires documented cleaning schedules as part of a building’s water management program. Skipping scheduled cleanings doesn’t just waste water — it can put your building out of compliance.
Ready to Find Out What You Could Save?
RPM Water Equity Solutions helps commercial facilities recover money lost to sewer billing assumptions. If your building has cooling towers, you may be paying sewer charges on water that never reaches the sewer system.
Request your free assessment today and find out how much you could recover.
Clean Towers Save Money
The cost of regular cooling tower cleaning is modest compared to the costs of neglect. A cleaner tower runs more efficiently, uses less water, requires less chemical treatment, and keeps you on the right side of health regulations. Build the twice-a-year minimum into your facility maintenance calendar and treat it as non-negotiable. Your water bills, your energy bills, and your compliance record will all benefit.
