Make up Water Treatment: Best Practices for Cooling Towers

Every cooling tower relies on a continuous supply of make up water to replace what’s lost through evaporation, drift, and blowdown. This makeup water is essential for maintaining the tower’s operation, but its quality varies widely depending on the source. Municipal supplies, well water, or even seawater each introduce different challenges into the system.

If not treated properly, poor-quality makeup water can cause scaling, corrosion, or biofouling. These problems reduce efficiency, shorten the lifespan of valves, piping, and other equipment, and drive up operating costs. For facility teams, treating makeup water correctly is one of the most important steps in protecting both the tower and the broader HVAC systems it supports.

Common Problems from Untreated Makeup Water

When makeup water is introduced without proper treatment, several issues can quickly occur:

• Scaling from calcium and magnesium minerals that deposit on heat transfer surfaces.
• Corrosion triggered by dissolved oxygen, chlorides, or low pH.
• Excessive solids that foul valves, strainers, and distribution decks.
• Microbial growth that clogs fill media and reduces cooling capacity.

These conditions may cause efficiency losses, increased downtime, or even system failure. Operators should view untreated makeup water as a sign of future maintenance headaches.

Why Pretreatment Is Required

Cooling towers are designed to concentrate water through evaporation. As water cycles through the system, contaminants in the makeup supply become more concentrated. Without a treatment plan in place, even small levels of hardness, silica, or chlorides in the source water will compound into serious operational problems.

That’s why most facilities incorporate pretreatment steps before the water ever enters the tower. Pretreatment reduces the load on downstream water chemistry programs and ensures that cooling tower maintenance efforts can actually hold.

Learn more about how R2J supports facility teams with full cooling tower water treatment programs designed to control scaling, corrosion, and biological growth.

Effective Strategies for Makeup Water Treatment

Filtration and Pretreatment

The first step in managing makeup water is removing suspended solids that may cause fouling inside the cooling tower. Pretreatment often includes multimedia filters, cartridge filters, or clarifiers. These systems are designed to improve water quality before it enters the tower, reducing the risk of scaling on valves, nozzles, and fill.

Facilities with challenging source water, including seawater, may require more advanced pretreatment such as reverse osmosis or softening to ensure the tower can operate at stable cycles of concentration.

Chemical Treatment

Once makeup water passes through pretreatment, chemical conditioning helps maintain system balance. Programs typically use:

• Corrosion inhibitors to protect steel and copper components from aggressive water chemistry.
• Dispersants to prevent scaling deposits on heat transfer surfaces.
• Biocides to control microbial growth that can clog fill, reduce efficiency, or cause problems with drift emissions.

The right mix of chemicals depends on the source water and the specific cooling system design.

Blowdown and Cycles of Concentration

Since evaporation and drift naturally concentrate minerals, regular blowdown is required to purge dissolved solids. Automated valves can be set to discharge a controlled volume of water when conductivity exceeds target levels.

Balancing blowdown is important: too much wastes water and treatment chemicals, while too little increases the risk of scaling and corrosion. Effective programs closely monitor conductivity to maintain the right cycles of concentration.

Monitoring and Control Systems

Modern cooling towers often rely on sensors and controllers to check pH, conductivity, and inhibitor residuals in real time. These control systems are designed to adjust chemical feed and blowdown rates automatically, making sure operators don’t rely only on manual testing.

By combining filtration, chemical treatment, and smart monitoring, facility teams can optimize makeup water use and reduce the total amount of water needed to keep the system running safely.

Learn how R2J delivers tailored cooling tower water treatment programs that provide lasting protection against scaling, fouling, and corrosion.

Best Practices for Make Up Water Treatment in Cooling Towers

Routine Monitoring and Maintenance

Even with a strong treatment program, cooling towers need consistent oversight. Facility teams should:

• Check valves and distribution piping regularly to confirm proper opening and flow.
• Record information from water testing logs or files to track changes over time.
• Ensure automated blowdown valves are set correctly to discharge only the volume required.
• Keep in mind that seasonal variation in the source water may cause sudden changes in chemistry.

These actions are important to maintain balance and prevent problems before they occur. By making small adjustments early, operators avoid large swings in cycles of concentration and unnecessary water losses.

Warning Signs of Make Up Water Issues

Operators should be alert for signs that make up water treatment isn’t holding. Common indicators include:

• Deposits or scaling found on fill media and tower decks.
• Rising blowdown volume, beyond what’s needed to control solids.
• Unexplained corrosion on piping, fittings, or valves.
• Fouling or blockages that restrict drift eliminators.

If these conditions are ignored, they may cause reduced efficiency, downtime, or even equipment failure. The type of problem often points directly to gaps in the treatment program.

Expert Support for Cooling Tower Makeup Water Treatment

Every site has unique conditions, and no single approach will meet all needs. That’s why partnering with an expert is essential. R2J provides comprehensive make up water treatment programs, making sure cooling towers are protected against scaling, corrosion, and microbial fouling.

We design strategies around the specific source water – whether municipal, well, or seawater – and deliver the content and technical information operators need to act confidently. Our programs are designed with operators in mind, ensuring preventive steps are easy to follow and backed by continuous testing.

Learn more about long-term benefits in regular cooling tower maintenance.

Contact R2J today to schedule a consultation and protect your cooling tower systems with reliable makeup water treatment strategies.

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