Top 10 Legionella Water Treatment Mistakes

Legionella Compliance Solutions

By: Chris Gauthier, President & Chief Science Officer


Having worked with large facilities worldwide for over 22 years, I’ve seen firsthand how these mistakes could have been avoided with the right planning. Below are the top 10 Legionella mistakes I often see when it comes to implementing Copper Silver Ionization (CSI) for large-scale facilities—and how to make sure you don’t fall into the same traps.

These top 10 Legionella water treatment mistakes should be avoided when choosing the right CSI Legionella water treatment system for a large facility. This is not just about picking a product—it’s a strategic decision that affects safety, compliance, and long-term expenses. For locations with over 190 healthcare beds or hotels with more than 150 rooms, the stakes are even higher. An underpowered or poorly designed CSI system can result in ineffective Legionella control, unexpected costs for upgrades, and compliance headaches down the road.

Scope of application: This top 10 Legionella mistakes prevention guideline applies to Legionella control copper-silver ionization solutions and compliance in various large-scale settings: healthcare, hotels, cruise ships, condos, office buildings, schools, military bases, government facilities, high-rise buildings, and more.


Mistake #1: Underestimating Power Needs for Big Facilities

A single cell (10A or 12A) CSI controller should be okay for smaller buildings (≤190 beds, ≤150 hotel rooms), but in a larger high-water load facility, it’s just not enough. Using several low-power controllers to cover a large facility will lead to inconsistent ion levels and a much higher relative cost compared to more powerful CSI controllers (20A and above).

What to Do Instead: Go for multi-drive CSI systems that range from 20A to 160A. These are made to handle larger water volumes with fewer units, lower setup costs, and more stable ion levels. CSIPhoenix® and CSIDefender® are engineered to deliver more power.


Mistake #2: Ignoring Water Load (Usage) Patterns

It’s not just about knowing your water volume. Complex water distribution networks with multiple loops and different flow rates can create problems that standard systems can’t manage. I’ve seen systems that looked good on paper but ended up failing to treat the sites of Legionella growth within the faiclity.

Avoid This By: Do a thorough daily and hourly water load assessment, including peak and off-peak flow rates. Check water pressure, pipe sizing, and the layout of your Domestic Hot Water (DHW) loops. Match your system to these specifics to keep ion levels balanced. This also applies to those favoring a point of entry (POE) type of application that also required more power and multiple cells to accomplish the Legionella compliance objectives.


Mistake #3: Relying on Just One Active Cell Without Automated Backups

Large facilities should never depend on a single active cell to handle the entire load. If that one cell fails, it disrupts the whole Legionella control process, leaving parts of the system vulnerable until it’s fixed. It’s like running a skyscraper with only one elevator—you need more to keep everything moving smoothly.

Solution: Opt for a multi-cell setup like the CSIPhoenix® system with the IonSafe™ backup feature. This setup provides independent activation and monitoring of multiple cells, ensuring continuous protection even if one cell needs servicing. The result? Consistent ionization, better reliability, and up to two years or more of operation before alloy replacements are required.


Mistake #4: Choosing Outdated Controllers

I’ve seen new construction projects using controllers that were designed over 20 years ago. They often lack basic features like multi-zone control, data logging, and safety backups, making Legionella compliance difficult.

Instead: Choose an industrial-grade CSI controller for large facilities. Those with Multi-DC output drive controllers like CSIPhoenix® can monitor and control each cell independently, adjust remotely, and have advanced safety features.


Mistake #5: Overlooking Water Quality Issues

Legionella control isn’t just about having enough copper-silver ionization power—it’s about water chemistry, too. Low or high hardness and Total Dissolved Solids (TDS) levels can make some CSI systems fail. Many facilities end up removing their CSI systems, thinking they don’t work, when the real issue is the lack of modern “Next-Gen” CSI engineering.

What to Do: Choose a “Next-Gen” CSI system like CSIPhoenix® with the DualArray™ feature. It’s built to handle both high and low TDS environments, ensuring stable performance even when water chemistry changes. Contact us for details.


Mistake #6: Skipping Regular Maintenance and Monitoring

In all facilities, regular CSI maintenance and monitoring are critical. Without them, even the best system will start to fail. I’ve seen systems fall apart simply because no one kept up with routine monthly chamber cell cleaning that takes 10 minutes.

How to Fix It: Use a system that includes automation, data logging, and remote monitoring with operational alarms. These features will help you stay on top of maintenance and ensure your system runs smoothly. You can also ask for automated “self-cleaning” CSI solutions provided as an options with the next-gen CSIPhoenix® line of copper-silver ionization solutions.


Mistake #7: Trying to Scale Up Small Systems Sold to Get in the Door

It’s tempting to just add more small controllers to handle a large facility, but this approach is expensive and messy. It’s also a classic sales tactic to get in the door and eventually upsell additional units. In the end, if one CSI unit fails, the whole system becomes compromised, and you’re left with high costs and less control.

Smarter Solution: Choose a high-power controller with multi-DC output drives built for large-scale facilities. Using one powerful unit reduces physical space by up to 70% and installation costs by up to 55%. You’ll also get it right the first time.


Mistake #8: Not Planning for Growth

Many facilities choose a system based only on their current size and needs. But if you expand or add new building areas, you may find that your system isn’t up to the task.

Avoid This By: Invest in a scalable system. CSIPhoenix® systems are designed to grow with your facility, allowing you to add more “snap-in” expansion modules and added chamber cells as needed (up to 160A and 16 cells) without having to replace everything.


Mistake #9: Applying One Control Strategy to Multiple Zones

Large facilities often have different areas with varying water needs. Trying to use one control strategy for each zones leads to added cost and additional technology footprint.

Better Idea: Implement a multi-zone CSI system that lets you control each (common mechanical room) DHW areas separately. This way, each zone of your building gets exactly what it needs yet by using a single more powerful controller.


Mistake #10: Forgetting About Compliance and Reporting

Meeting compliance standards isn’t just a suggestion—it’s usually a legal requirement. But many facilities don’t have systems that offer full data tracking and reporting, which can cause trouble during audits.

Solution: Use a system like CSIPhoenix® with built-in data logging, reporting, and BMS compatibility. This makes it easier to meet regulatory requirements and keeps you audit-ready.


Final Thoughts

Each of these top 10 Legionella mistakes can cost you time, money, and peace of mind—but they’re preventable. Don’t settle for a copper-silver ionization system that’s just “good enough.” Invest in a multi-DC output drive solution that’s built to handle the challenges of large facilities.

Want to know more? Contact us to see how our CSIPhoenix® controllers with IonSafe™ and chamber cells with DualArray™ can give your facility the Legionella control you need.

Comments are closed