Background
A skilled nursing and rehabilitation facility in the Midwest partnered with IWC Innovations to conduct routine Legionella testing as part of its water management program. Initial sampling included two water samples, one of which tested positive for Legionella pneumophila serogroup 1, the strain most commonly associated with Legionnaires’ disease.
Given the positive result and the vulnerable population served by the facility, IWC recommended expanded representative environmental testing to determine the extent of contamination throughout the building’s potable water system.
The Challenge
IWC developed a comprehensive sampling plan that included 15 additional water samples collected from representative locations throughout the facility.
The expanded testing revealed widespread colonization:
- Initial routine samples: 1 of 2 positive for L. pneumophila serogroup 1
- Expanded sampling: 12 of 15 additional samples positive for L. pneumophila serogroup 1
The results confirmed that the bacteria had colonized much of the building’s water distribution system, creating a significant risk for residents, staff, and visitors.
IWC's Approach
Following confirmation of widespread contamination, IWC recommended an immediate chemical shock remediation of the potable water system.
IWC deployed a team of remediation specialists to perform an acute sanitization of the facility’s potable water system using the HydroTreat™ Process.
The remediation included:
- Conducting a detailed pre-remediation planning meeting with facility leadership.
- Isolating sensitive equipment and preparing the plumbing system by shutting down hot water heaters and draining storage tanks.
- Injecting HydroTreat™, sodium hypochlorite and chlorine dioxide into the facility’s incoming water supply using high-pressure pumps.
- Monitoring distal outlets throughout the building until a hyperchlorination residual exceeding 200 ppm was achieved across both hot and cold water systems.
- Maintaining the disinfectant concentration for a minimum three-hour contact time in accordance with AWWA sanitization protocols.
- Methodically flushing every outlet throughout the facility until free chlorine levels returned to safe operating levels below 2 ppm before returning the system to service use.
Following completion of the remediation, IWC met with facility leadership to review next steps and provide recommendations for ongoing water system management.
The Results
- Conducted follow-up environmental testing after remediation and system flushing.
- Post-remediation testing found no detectable Legionella throughout the potable water system.
- Successfully restored the safety of the facility’s water system.
- Implemented long-term water management recommendations to reduce the risk of future Legionella growth.
- Combined rapid response, comprehensive remediation, and ongoing prevention to achieve a successful outcome.
Long Term Recommendations
Recognizing that remediation alone does not prevent future colonization, IWC recommended several proactive measures to maintain a safe building water system:
- Implement a comprehensive Water Management Program aligned with ASHRAE Standard 188 and CDC guidance.
- Perform quarterly Legionella testing to validate ongoing program effectiveness.
- Monitor disinfectant residuals and hot water temperatures throughout the distribution system.
- Eliminate plumbing dead legs wherever possible and establish routine flushing protocols for infrequently used fixtures.
- Install 0.2-micron medical-grade Legionella in-line filters on ice machines where appropriate.
- Flush vacant rooms and low-use fixtures weekly—or twice weekly in high-risk areas—to prevent water stagnation.
Conclusion
Routine water testing identified Legionella pneumophila serogroup 1 before any known cases of Legionnaires’ disease occurred, enabling the facility to respond in a proactive manner rather than reactive manner.
Expanded representative environmental sampling confirmed widespread colonization throughout the potable water system, prompting immediate corrective action. IWC successfully remediated the system using its HydroTreat™ Process, and follow-up testing confirmed that no detectable Legionella remained after treatment. In addition to restoring the safety of the building’s water system, the facility received comprehensive recommendations for long-term compliance with ASHRAE Standard 188 and CDC guidance, providing a sustainable framework to reduce future Legionella growth risks and help protect its highly vulnerable resident population.
