Overview
Ice machines are a known contamination risk in food service environments due to persistent moisture, organic buildup, and limited accessibility for routine cleaning. Microbial contamination, including bacteria and fungi, can persist even under standard sanitation protocols.
This case study evaluates the performance of a chlorine dioxide–based gas system (CleanAir) in reducing microbial contamination inside commercial ice machines at a large hospitality facility.
Objectives of Testing
The primary objective was to assess whether a passive chlorine dioxide system could:
- Reduce bacterial and fungal contamination inside ice machines
- Maintain sanitation without repeated manual cleaning
- Control key pathogens including E. coli, Listeria, and Legionella
Improve overall cleanliness and safety under normal operating conditions
Testing Methodology
On April 4, 2023, multiple ice machines across the Orlando Resort were sampled following routine internal cleaning.
Swab samples were collected from internal components including:
- Tracks
- Doors
- Walls
- Lids
After initial sampling:
- Machines received a partial cleaning using an EPA-registered disinfectant
- CleanAir chlorine dioxide generators were installed
- No additional cleaning was performed during the study period
- Machines continued normal daily use
Follow-up sampling occurred on:
- April 25, 2023
- May 17, 2023
- June 15, 2023
All samples were analyzed by a CDC-partnered laboratory.
Results
Baseline Conditions (Pre-Treatment)
Initial testing revealed widespread contamination across all machines:
- Bacterial and fungal counts reached as high as 19,200,000 CFUs
- Mold was visibly present on internal surfaces and gaskets
- Listeria was detected in all machines tested
- E. coli and Legionella were not detected at baseline
These results confirm that standard cleaning alone was insufficient to control microbial buildup.
Post-Treatment Performance
Following CleanAir installation, microbial counts dropped sharply across all measured locations.
Banquet Service Corridor #1
- Track: 19,000,000 → 130 → 120 CFUs
- Door (Right): 19,200,000 → None → 50 CFUs
- Wall surfaces: Reduced to non-detectable levels
Banquet Service Corridor #2
- Track: 17,400,000 → 1,190 → 30 CFUs
- Lid: 10,000 → None → 30 CFUs
Guest Tower (5th Floor)
- Door surface: 6,400,000 → 220 → 20 CFUs
- Wall contamination reduced to non-detectable
Palms Meeting Space
- Track: 15,000,000 → 130 → 300 CFUs
- Wall: 3,650,000 → 0 → None
6th Floor Guest Tower
- Door: 15,700,000 → 220 CFUs (no final test)
Pathogen Findings
Across all post-treatment samples:
- E. coli: Not detected
- Legionella: Not detected
- Listeria: Present but not quantified
Discussion
The data shows a consistent and significant reduction in microbial load following installation of the chlorine dioxide system.
Key observations:
- CFU reductions reached several orders of magnitude across all machines
- Sanitation was maintained without additional cleaning after installation
- Performance was achieved under real-world usage conditions
- Even incomplete initial cleaning did not prevent strong results
The persistence of unquantified Listeria suggests that while the system significantly reduces contamination, it may function best as part of a broader sanitation program rather than a complete replacement for deep cleaning.
Summary
The CleanAir system demonstrated the ability to:
- Dramatically reduce bacterial and fungal contamination
- Maintain low microbial counts over time
- Eliminate detectable E. coli and Legionella
- Operate continuously without added labor
In addition to quantitative improvements, qualitative benefits were observed, including cleaner internal surfaces and improved odor conditions.
Study Conclusion
This study supports the use of chlorine dioxide gas systems as an effective, low-maintenance solution for controlling microbial contamination in ice machines.
The technology provides:
- Continuous antimicrobial action
- Reduced reliance on manual cleaning
- Improved sanitation consistency
- Lower operational labor requirements
Based on these findings, continued use across all ice machines was recommended to maintain food safety standards and reduce contamination risk.
See how ice machine sanitation helps maintain cleaner machines and safer ice.