Legionella Risk Assessment: Protecting Water Systems

Why Legionella Risk Assessments Matter

Legionnaires’ disease is a potentially fatal form of pneumonia caused by breathing in water droplets that contain contaminated water Legionella bacteria. These bacteria thrive in manmade water systems – particularly those with warm temperatures, low flow, or aging infrastructure. If left unchecked, they can spread through plumbing, showers, decorative fountains, and cold water systems, putting building occupants at serious risk.

A Legionella risk assessment is the first step in identifying where that risk exists. It helps duty holders, facility managers, and landlords understand how their system operates, identify risk factors where control may be lacking, andwhat needs to be done to prevent exposure. Risk isn’t always visible. It builds quietly – through stagnation, inconsistent maintenance, or overlooked equipment – and turns deadly when conditions align.

Performing a detailed assessment helps protect not only public health but also the reputation and liability of the facility. In many cases, it’s not optional. Depending on your state, building type, or industry, health regulations, safety legislation, and approved codes of practice may require you to identify risks, develop control measures, and implement testing protocols to stay compliant.

 

What Is a Legionella Risk Assessment?

A Legionella risk assessment is a structured review of your building’s water systems, designed to identify the conditions that support Legionella growth and transmission. It focuses on:

• System layout: Are there dead legs, infrequently used outlets, or sections prone to stagnation?
• Water temperatures: Do hot water systems reach and maintain >140°F? Are cold water systems staying below 68°F?
• Preventative Measures: Are there flushing routines, regular disinfections, or secondary treatment systems in place?
• Operation and maintenance: Is there documentation of previous testing, cleaning, or remediation efforts?

This assessment must be carried out by a competent person – either trained staff or a third-party water treatment provider familiar with relevant health and safety law. Once complete, it provides the foundation for a written control scheme and ongoing monitoring plan.

Learn more about our Legionella testing and additional water safety measures.

Where Legionella Risk Comes From

Legionella doesn’t need much to take hold – just the right conditions and a system no one’s watching closely. That’s why risk often exists in places most people don’t think to check: a low-use restroom, an unused hose bibb, a warm storage tank in a mechanical room.

Water systems are most vulnerable when they’re inconsistent. Irregular temperatures, low flow, or outdated plumbing can all create pockets of stagnation. In those pockets, biofilm forms, temperatures drift into the bacterial growth range (68–122°F), and scale or sediment builds up. This becomes the perfect breeding ground for Legionella bacteria.

Systems at highest risk include:

• Showers and locker rooms in gyms, schools, or healthcare facilities
• Cooling towers and evaporative condensers
• Hot tubs, decorative fountains, and other aerosol-generating water features
• Domestic properties with aging plumbing or little water turnover
• Commercial buildings where seasonal shutdowns or remote areas of the plumbing go unused

Even a modern building can become a problem if maintenance routines slip or system upgrades introduce new risk factors (like new storage tanks, added pipe runs, or more endpoints).

Conducting a Proper Risk Assessment

A quality Legionella risk assessment isn’t a template. It’s a building-specific walkthrough of the actual conditions – not just theory. It requires someone to be on-site, open panels, trace pipework, take readings, and ask questions.

Steps typically include:

• Mapping out all hot and cold water systems, from entry point to endpoint
• Taking temperature measurements at tanks, outlets, and return lines
• Identifying low-use or dead-end sections of pipework
• Reviewing preventative measures already in place (if any)
• Evaluating how maintenance is carried out – or not
• Flagging any immediate compliance gaps with local codes or best practice guidance

If needed, the assessor may also recommend Legionella testing to establish whether contamination is already present or to verify the effectiveness of current controls.

High-risk properties – like healthcare centers, senior living communities, or facilities with complex water systems – should conduct assessments more frequently, especially if there’s been a system change or previous evidence of Legionella.

Learn how Legionella Water Management Programs help prevent outbreaks and reduce long-term exposure risks.

After the Assessment: Turning Insight Into Action

A risk assessment means nothing if it sits in a folder. Once complete, the findings need to be turned into a clear, actionable plan that reduces exposure, supports compliance, and holds up under regulatory review.

This typically includes:

• A written scheme of control outlining specific actions to manage the risk
• Defined roles and responsibilities for those maintaining the system (including the operators and responsible person)
• A monitoring schedule for temperature checks, flushing routines, and system inspections
• Corrective actions for non-compliant or at-risk system elements
• Documentation protocols to ensure evidence is available if the system is ever audited

High-risk properties may also need to develop a Legionella Water Management Plan, particularly in healthcare, education, or multi-tenant facilities. These plans provide a more detailed framework for ongoing control and are often tied to industry guidance and health department oversight.

Most importantly, any plan should be reviewed regularly – at least annually, or anytime the water system is altered, occupancy patterns shift, or new exposure risks are introduced.

How R2J Supports Legionella Risk Management

R2J helps building owners, managers, and safety officers stay ahead of Legionella risk – not just by identifying vulnerabilities, but also by helping produce and implement long-term solutions that work.

Our team provides:

• On-site risk assessments carried out by trained professionals familiar with state and local regulations
• Development of written water safety and monitoring plans tailored to your building’s layout and water usage patterns
• Regular Legionella testing, flushing protocol support, and water temperature monitoring
• Remediation guidance in the event of a failed test or known exposure risk
• Ongoing documentation and reporting to support health inspections or internal audits

Whether your building is large or small, complex or straightforward, we help ensure that you meet legal obligations and reduce the chance of a costly outbreak.

Learn more about Legionella remediation and water safety planning at R2J.

Frequently Asked Questions

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Protect Your System, Protect Your People

Legionella risk won’t fix itself. The longer a system goes without being assessed, the more opportunity bacteria have to grow – and the more liability sits on your shoulders.

If you manage a facility with water systems and are concerned about where your risks lie, start with a conversation. R2J helps facilities across Florida conduct formal risk assessments, implement water safety plans, and meet all relevant compliance standards.

Contact us today to schedule your assessment and take the first step toward safer water systems.