Legionella Risk Assessment Services in the U.S.

What is a Legionella risk assessment or Legionella root cause assessment? A Legionella risk assessment (or Legionella root cause assessment if Legionella is present) is the evaluation of your facility’s unique characteristics and environment to identify Legionella risk factors and/or root causes, and develop an appropriate water management plan and related Legionella testing, mitigation, or remediation steps as needed.

Legionella Risk AssessmentA Legionella risk assessment / Legionella root cause assessment is “Step 4: Identification of Potential Legionella Risks (Hazard Analysis)” in the development of a water management program.

Note: The following Legionella risk assessment information is based on U.S. regulations and requirements. Be careful when you search for Legionella information on the internet because UK or European websites may offer Legionella risk assessment information that differs from U.S. requirements.

Why a Legionella Risk Assessment Matters

If you are concerned about Legionella or Legionnaires Disease, your first step is to contact a Legionella control specialist with engineering expertise so they can help you find both a solution and the root cause so you can keep Legionella from coming back. Legionella Control Systems offers a holistic assessment that considers your entire water management environment such as piping complexity, system age, water stagnation and recirculation, biofilm growth, temperature, residual disinfectant, and more. Legionella risk factors, root causes, and solutions are complex, so there is no “one size fits all” solution, and you should be wary of any Legionella “expert” who claims to be able to diagnose and provide a solution without a thorough root cause investigation.

Your initial contact will be followed by a discussion that will lead toward the risk assessment phase. The discussion will cover environmental factors, risk factors for people in your facility, and regulations that may affect your industry. A risk assessment and site visit is often a critical next step toward your immediate and long-term water safety, Legionella risk management, and pathogen control.

As a result of all of this, Legionella Control Systems’s evaluation as a Legionella consultant helps to reduce your risk and liability while setting the stage for effective solutions. As noted above, it is unusual if a Legionella consultant could completely and safely diagnose and solve your water safety issues over the phone, so you should be wary of companies that immediately propose a solution without understanding and physically examining your systems.

Have you previously had a Legionella risk assessment? Learn 5 Reasons You Should Get a Second Opinion on Your Risk Assessment.

What Happens During a Legionella Risk Assessment

During the risk assessment, a Legionella control expert will consider factors such as your specific plumbing design, components, and water characteristics. As a truly independent Legionella consultant, Legionella Control Systems’s experts will provide an outside perspective that dives deeply into your safety concerns with Legionella as well as other waterborne pathogens. Our Legionella expert will then troubleshoot problem areas and provide a baseline review of existing systems, components, and Legionella risk factors.

Legionella Control Systems offers risk assessments and Legionnaires site visits on an independent consulting basis. An assessment gives you peace of mind because it results in expert Legionella diagnostics and documented solutions, both of which are important in reducing your Legionella liability and risk. Our experience in working with diverse water systems across countless facilities and industry segments within healthcare, hospitality, and industry will guide you towards a safe water system and help you safeguard people while protecting yourself from Legionella risk. Put simply, a small amount of our time can save lives, protect health, and potentially save millions of dollars in liability costs. Our insights can help you document your mitigation efforts and effectively reduce dangerous water including pathogens. Contact us right now to discuss your situation and then schedule a Legionella risk assessment at your facility.

What Your Legionella Risk Assessment Site Visit Will Address

What May Be Included in a Legionella Risk Assessment Site Visit

  • Review of water systems in building
  • Softeners, Filters
  • Heaters
  • Hot and Cold Holding Tanks
  • Piping
  • Any other parts of the water system
  • Review of risk factors unique to the facility
  • Local Water Information and Testing
  • Conductivity
  • Hardness
  • ORP
  • Free Chlorine
  • pH
  • Temperature
  • Pressure
  • Provide Engineering Report
  • Detail of the current state of risk factors related to the building
  • Findings
  • Test Results
  • Lab Results (if applicable)
  • Recommendations to mitigate current or potential Legionella outbreak
  • Immediate, midterm and long-term steps
  • Recommendations on Water Management Plan

What You Receive After the Assessment

Professional engineering Legionella risk assessment / root cause reports are created for every visit with recommendations to help you keep your clients and staff safe. This documentation is an essential component of your mitigation and risk reduction.

Legionella Risk Assessment Frequently Asked Questions

What is a Legionella risk assessment?

A Legionella risk assessment in the United States involves identifying and evaluating the risks of Legionella bacteria in water systems. This assessment examines factors like water temperature, chemical properties of water, flow, plumbing design and areas where water might stagnate, which can encourage waterborne pathogenic bacterial growth. The primary goal is to detect potential risks and implement control measures to prevent an outbreak of Legionnaires’ disease.

Do I need a Legionella risk assessment if I already test my water?

Though Legionella testing is an important part of a water management program, testing does not paint a full picture of risks and hazards in your facility. Knowing the fundamentals of your building’s risk factors in different areas is much more valuable than knowing what has happened in the past with spot testing. Assessments when paired with testing tell you much more about your building than testing alone.

Who is responsible for conducting a Legionella risk assessment?

In the U.S., building owners, employers, or property managers are typically responsible for ensuring a Legionella risk assessment is conducted. These individuals must ensure the assessment is carried out by someone with appropriate training and knowledge in Legionella and waterborne pathogen control, often referred to as a “competent person.” Legionella Control Systems has degreed engineers on staff and utilizes the Professional Qualifications Standard for Legionella Water Safety and Management Personnel, ASSE/IAPMO/ANSI 12080. Our staff have attained ASSE 12080 Legionella Water Safety and Management Specialist Certification.

How often should a Legionella risk assessment be conducted?

The assessment should be reviewed and updated regularly, especially after significant changes to the water system, building usage, or if an incident of Legionnaires’ disease occurs. While there is no federal mandate for an annual review, it is considered best practice to conduct an Legionella risk assessment every year from an independent consultant to maintain ongoing safety.

What should be included in a Legionella risk assessment?

The assessment should include a thorough evaluation of the water system’s design, usage patterns, and maintenance history. It should identify areas where Legionella could potentially grow, assess existing control measures, and recommend additional actions if necessary. Proper documentation of findings and a detailed action plan are crucial components of the assessment.

Is Legionella testing necessary during the assessment?

Although not legally required in all cases, Legionella testing is often recommended, particularly in high-risk environments like healthcare facilities or large commercial buildings. The decision on whether, where, and how to conduct testing during a risk assessment should be considered on a case by case basis, and depends on the current status of the existing water management program.

Can I conduct the Legionella risk assessment myself?

If you have sufficient knowledge and experience in managing Legionella risks, you can theoretically conduct the assessment yourself. However, for reasons of risk, accuracy, and liability, it is advisable to hire a qualified Legionella control professional, particularly for complex water systems or high-risk environments, to ensure all potential risks are thoroughly identified and managed.

What are the legal requirements regarding Legionella risk assessments?

In the United States, guidelines from OSHA (Occupational Safety and Health Administration) and the CDC (Centers for Disease Control and Prevention) emphasize the importance of managing Legionella risks, especially in environments such as hospitals and healthcare facilities. Although there is no federal law that mandates Legionella risk assessments for all buildings, failing to manage Legionella risks can result in violations of OSHA’s General Duty Clause, which requires employers to provide a safe work environment. Moreover, there are requirements for healthcare facilities from CMS among other organizations – see the Legionella-related requirements for healthcare facilities.

How do we get started on a Legionella risk assessment?

To plan your next steps for Legionella risk assessments, contact the Legionella experts at Legionella Control Systems.

By Chris Nancrede. Last Updated: September 23, 2026

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