What Does a Cooling Tower Maintenance Program Actually Include? A Breakdown for Building Operators

Quick answer: A cooling tower maintenance program includes routine chemical treatment and water testing, monthly Legionella culture testing, quarterly corrosion monitoring, physical cleaning and disinfection of the tower basin and components, and an annual system review. Each element serves a specific purpose in keeping the system safe, efficient, and compliant.

Building and plant operators regularly search for what a cooling tower maintenance program should include, often at the moment they are evaluating whether their current provider is actually meeting their needs. It is the right question to ask. Not all programs are built the same, and the difference between a thorough program and a minimal one shows up in energy costs, equipment life, and risk exposure.

Here is a straightforward breakdown of what a properly structured cooling tower maintenance program covers and why each component matters.

Routine Chemical Treatment and Water Testing

The foundation of any cooling tower maintenance program is consistent chemical treatment and water chemistry monitoring. Cooling towers operate in open-loop conditions, constantly losing water to evaporation and continuously drawing in outside air. That means ongoing exposure to dissolved minerals, organic matter, and airborne contaminants that drive scale, corrosion, and biological growth if left uncontrolled.

A properly maintained tower requires a treatment program that addresses all three threats simultaneously: scale inhibitors to prevent mineral deposition on heat transfer surfaces, corrosion inhibitors to protect the system’s metal components, and biocides to control bacterial growth and biofilm development.

Water chemistry should be tested weekly at minimum. Key parameters include pH, conductivity, inhibitor concentrations, and biocide residuals. Cycles of concentration, the ratio of dissolved solids in the circulating water versus the make-up water, should be verified bi-weekly. Running outside of target cycles wastes chemistry and water, and at worst, accelerates the very fouling and scaling the treatment program is designed to prevent.

Legionella Testing and Biological Control

Cooling tower Legionella prevention is not optional, and it is not adequately addressed by visual inspection or general biocide treatment alone. Legionella culture testing should be conducted monthly on any actively operating cooling tower. This is the minimum standard set out in PWGSC MD 15161, a federal benchmark developed by Public Services and Procurement Canada and adopted nationally as best practice for Legionella control in mechanical systems, and it aligns with Quebec’s RBQ Safety Code requirements.

Total aerobic bacteria counts and heterotrophic plate counts should also be monitored monthly during the operating season. Elevated counts are an early warning that the biocide program is underperforming or that biofilm has developed in a section of the system that is not getting adequate treatment or flow.

A cooling tower maintenance program that does not include monthly Legionella testing may fall short of widely adopted Canadian best-practice guidelines and applicable provincial or regional requirements. If your current program tests quarterly or annually, that gap is worth reviewing.

In a commercial building, a lapsed testing cycle is a compliance gap. In a manufacturing or food processing facility, the same lapse puts a production-critical cooling system on the wrong side of both Legionella risk and process reliability, since the tower is often supporting equipment cooling as well as comfort cooling.

Corrosion Monitoring

Corrosion coupon monitoring is a standard part of any credible cooling tower maintenance program. Coupons, small metal specimens installed in the water flow path, measure actual metal loss over a defined exposure period. They should remain in place for a minimum of 90 days, then be removed, cleaned using standardized procedures, and reweighed. The resulting corrosion rate, expressed in mils per year (MPY), tells you directly whether your inhibitor program is holding.

Elevated corrosion rates are a leading indicator of future system failures, not a lagging one. A chemistry adjustment based on a coupon result is a fraction of the cost of replacing a heat exchanger that failed because nobody was watching the trend.

Physical Cleaning and Disinfection

Chemical treatment is not a substitute for physical cleaning. Cooling towers accumulate sediment, scale, biofilm, and organic debris over time. The basin, fill media, distribution nozzles, and drift eliminators all need to be physically inspected and cleaned on a defined schedule.

The most important cleaning event is the seasonal startup. A tower that has been shut down over winter has been sitting with stagnant water in some or all of its components. Stagnant water is one of the most consistent precursors to elevated Legionella counts. Before a tower goes back into operation, the program should include a documented startup protocol: drain and flush the basin, clean accessible components, refill with treated water, and conduct a Legionella test before resuming normal operation.

Mid-season cleaning, particularly of the basin and fill, may also be warranted depending on system conditions, local water quality, and biological activity. Your water treatment provider should be specifying cleaning frequency based on what the chemistry and coupon data are actually showing, not on a fixed calendar that ignores system conditions.

Documentation and Recordkeeping

A cooling tower maintenance program is only as good as the documentation behind it. Test results, service records, corrective actions, cleaning logs, and Legionella testing outcomes should all be retained in a format that can be reviewed, audited, and produced if a public health authority ever asks to see your program.

Documentation serves two purposes. First, it is how your team tracks whether the program is actually working. Second, it is how you demonstrate due diligence if something goes wrong. A facility that can show consistent, documented maintenance and testing is in a fundamentally different position than one that cannot.

Pace Solutions’ e-Service Reporting platform gives facility managers a full record of every test result, service visit, and corrective action taken on their systems, accessible when needed rather than buried in paper files.

Annual System Review

Once a year, the cooling tower should undergo a comprehensive review covering the full physical inspection, a review of the written water management program, and a check of any changes in occupancy, system configuration, or local make-up water quality. If anything has changed that affects the risk profile of the system, the treatment program should be updated accordingly.

Make-up water quality can shift, particularly in municipalities that adjust treatment seasonally. An annual review ensures the program stays calibrated to current conditions rather than running on assumptions set at installation.

Is Your Current Program Covering the Bases?

Building and plant operators who are evaluating whether their current cooling tower maintenance provider is meeting their needs should be able to get straightforward answers to these questions:

• Are we testing for Legionella monthly during the operating season?
• Are corrosion coupons in place and being pulled quarterly?
• Is there a documented startup protocol that runs before the tower goes online each season?
• Are test results being reviewed against control targets, with corrective action documented when targets are missed?
• Is there a written water management program that reflects current system conditions?

If the answer to any of these is uncertain, that is the conversation worth having. Pace Solutions works with industrial and commercial building operators and property managers across Canada to assess cooling tower programs and close the gaps. Contact your regional Pace representative to get a clear picture of where your program stands.