Understanding Legionella: Why It’s a Growing Concern

Legionella is a genus of bacteria that occurs naturally in freshwater environments, such as lakes and streams. In those settings, the bacteria rarely pose a threat. But in engineered environments – specifically building water systems – conditions can allow Legionella to multiply and become dangerous. When people inhale aerosolized droplets containing the legionella bacteria, they may develop respiratory illnesses ranging from mild flu-like symptoms to severe pneumonia known as Legionnaires’ disease.

The illness is particularly serious for individuals with compromised immune systems, such as hospital patients, the elderly, or people with underlying lung conditions. In healthcare and residential care facilities, even a single Legionella bacteria incident can have major public health and legal consequences.

According to the CDC, most Legionnaires’ disease outbreaks in the U.S. are linked to water system failures – not contaminated source water. That means outbreaks are preventable if building water systems are properly designed, maintained, and monitored.

Source: Centers for Disease Control and Prevention (CDC). Legionnaires’ disease in the United States, 2000–2021.

How Legionella Grows and Spreads in Building Water Systems

Legionella bacteria multiply in warm, stagnant water. The ideal growth range is between 77°F and 113°F (25°C-45°C), but the bacteria can survive at broader temperatures depending on system conditions. Once established, Legionella spreads through aerosolized water droplets and infects people when inhaled.

These droplets can be generated by:

• Cooling tower drift
• Hot and cold water outlets
• Showerheads and faucets
• Decorative fountains
• Hot tubs and therapy pools
• Air conditioning systems using evaporative cooling

The risk is highest when a building’s water system contains areas of low flow, poor temperature control, or inadequate disinfectant residuals. Water heaters, storage tanks, long piping runs, and underused fixtures can all become reservoirs for Legionella growth.

In many outbreaks, investigators identify a mix of contributing factors: scale buildup, biofilm, loss of disinfectant, and fluctuating temperatures. These conditions are often worsened by poor maintenance practices or lack of oversight in complex plumbing systems.

Why Building Water Systems Are Vulnerable

Modern buildings, especially large ones, often have complex water systems that make it difficult to maintain uniform temperatures and flow. Some buildings have multiple water heaters, sprawling piping networks, and intermittent water use patterns that lead to stagnant water in certain areas. Even well-designed systems can become risky over time if they’re not actively managed.

Common risk points include:

• Hot water loops with return temperatures below 124°F (51°C)
• Cold water systems where ambient heat raises water temperature above 68°F (20°C)
• Storage tanks that allow thermal stratification or lack frequent turnover
• Mixing valves or tempering devices that unintentionally lower temperatures
• Infrequently used outlets, like spare bathrooms or underutilized wings
• Plumbing systems with “dead legs” or capped-off branches that trap water

These factors are often invisible in day-to-day operations, but they can create perfect conditions for Legionella growth. Inconsistent disinfection or loss of chlorine residual only increases the risk.

Public Health, Legal, and Operational Risks

Legionnaires’ disease isn’t just a theoretical risk. It causes hundreds of hospitalizations each year and is considered one of the most preventable building-related illnesses. Legionnaires disease can be fatal – especially in high-risk environments like hospitals, long-term care facilities, and senior housing.

In recent years, health departments have become more aggressive in investigating legionella bacteria outbreaks. Building owners and facility operators are increasingly held accountable for failing to manage water systems responsibly. In addition to health consequences, a confirmed legionnaires disease case tied to your building may lead to:

• Regulatory violations and corrective orders
• Legal claims and reputational damage
• Loss of CMS certification in healthcare environments
• Disruption of normal operations due to remediation protocols

A single incident is often enough to trigger permanent policy change – or in some cases, litigation.

For a summary of current requirements, outbreak investigations, and jurisdictional actions, visit EAI’s Legionnaires’ Regulations and Guidelines overview.

Common Sources and Risk Factors in Building Water Systems

Legionella bacteria aren’t distributed evenly throughout a building – they colonize in specific conditions. Knowing where to look is critical for any facility trying to stay ahead of an outbreak or meet compliance expectations.

In most commercial or institutional buildings, risk is highest in parts of the system where water is warm, stagnant, or not properly treated. This includes both potable and non-potable systems.

Hot Water Systems: A Prime Growth Environment

Hot water is meant to protect against microbial growth, but it often ends up encouraging legionella growth when temperatures aren’t properly maintained.

Key risks include:

• Inconsistent water temperatures – If water storage falls below 140°F (60°C) or delivery drops below 120°F (49°C), conditions favor Legionella bacteria multiplication.
• Tempering valves and recirculation loops – These can create cooler zones in distal piping, especially when return temperatures drop below safe limits.
• Scale and sediment buildup – These create surfaces where biofilm and bacteria can thrive, shielding them from disinfectants.
• Large-volume heaters or tanks – Poorly mixed or oversized systems allow for thermal stratification, leaving cold zones in supposedly hot water.

Because plumbing systems vary widely in design and use, it’s common for even “safe” systems to have isolated areas of risk – particularly in older facilities or those with decentralized heating systems.

Cold Water Systems: Often Overlooked, Still at Risk

Legionella is often associated with hot water, but cold water systems aren’t immune. When cold water warms above 68°F (20°C), legionella bacteria can begin to grow, albeit more slowly. Risk increases when water stagnates or loops are rarely used.

Typical issues include:

• Low-flow conditions – In buildings with oversized piping, water may not turn over frequently enough to maintain quality.
• Sunlight or radiant heat gain – Uninsulated plumbing exposed to warm mechanical rooms or ceilings can lead to thermal elevation.
• Contaminated backflow or cross-connections – These introduce organic material and can introduce bacteria from other parts of the building.
• Poor storage tank management – Tanks with long residence times, internal scaling, or inadequate mixing allow Legionella contamination to begin unnoticed.

In many outbreaks, cold water storage tanks or underused wings of the building have been identified as persistent reservoirs of legionella growth and/or contamination.

Plumbing Layout and the Entire Building Water System

The more complex the building, the more likely it is that the entire building water system may contain multiple legionella growth risk zones.

Common risk factors tied to design and use:

• Dead legs and capped tees – These are lengths of pipe no longer in service but still holding water. Without flow, they become legionella bacteria breeding grounds.
• Abandoned outlets or disused restrooms – Low-use fixtures allow disinfectant residuals to dissipate and water to go stagnant.
• Frequent use of pressure-reducing valves – These can create low-velocity zones where biofilm containing legionella species establishes itself.
• Inadequate flushing protocols – Especially in dormitories, healthcare, or buildings with seasonal use.

Even well-maintained systems can develop legionella growth risk over time due to load changes, occupancy shifts, or expansions that aren’t properly integrated into the existing water management program.

Storage Tanks and Holding Systems

Any place where water is stored – even temporarily – poses risk if turnover isn’t controlled. That includes:

• Cold and hot water storage tanks
• Break tanks or buffer tanks
• Graywater recovery systems
• Ice machines and humidifiers with reservoir-style designs

Each of these must have routine water quality monitoring, be regularly inspected, cleaned, and flushed to prevent bacterial growth and potential contamination of the broader system.

The Role of Water Flow and Temperature Control

Legionella thrives when water sits still and warms up. Systems that maintain continuous water flow, strong temperature control, and stable disinfectant residuals are significantly less likely to experience outbreaks.

That’s why most water management programs now require mapping of system temperatures, pressure zones, and flow profiles – not just general water quality monitoring or legionella testing. A small loop at the edge of a building may be functionally invisible until it causes a problem.

Regulatory Requirements and Legal Risk in Legionella Control

The regulatory landscape around Legionella has shifted dramatically in the past decade. What was once treated as a best-practice recommendation is now backed by enforceable guidelines, industry standards, and legal precedent.

Facilities that fall short – not just in execution but in documentation – can now face fines, loss of accreditation, or civil litigation. Whether you operate a hospital, university campus, long-term care facility, or commercial building, you are increasingly expected to have a formal Legionella monitoring and water management program in place.

ASHRAE 188: A Foundational Standard

ASHRAE Standard 188, titled Legionellosis: Risk Management for Building Water Systems, was released in 2015 and remains the primary technical framework used by both health departments and enforcement agencies. It outlines how facilities should identify, monitor, and control Legionella growth in both potable and non-potable systems.

The standard applies to:

• Healthcare facilities
• Hotels and resorts
• Commercial buildings with centralized hot water
• Multi-residential facilities
• Facilities with cooling towers, whirlpools, fountains, or humidifiers

ASHRAE 188 requires that building owners and managers:

• Perform a system-specific risk assessment
• Develop a written water management program
• Identify control points and establish control limits
• Implement routine Legionella testing or verification strategies
• Document all monitoring and corrective actions

It doesn’t replace local health code – but many jurisdictions now cite it when enforcing disease control and prevention efforts in buildings as well as establishing water quality monitoring standards.

CMS Expectations for Healthcare Facilities

In 2017, the Centers for Medicare & Medicaid Services (CMS) issued a memo to all certified healthcare facilities requiring them to implement infection prevention protocols specific to Legionella control. The guidance was not optional – it tied Legionella testing and management directly to a facility’s participation in Medicare and Medicaid funding programs.

Facilities must:

• Identify all building water systems that pose Legionella risk
• Develop and implement a water management program that complies with ASHRAE 188
• Specify testing protocols and response strategies
• Maintain records that can be reviewed during CMS inspections
• Monitor water quality on a routine and systemized basis

Non-compliance may result in Condition-level Deficiencies, loss of reimbursement, or referral to local health departments. For critical access hospitals and long-term care providers, the stakes are high – and CMS has made it clear that they expect formal programs backed by documentation.

CDC Guidance and Toolkit

The CDC offers a Legionella Water Management Toolkit that mirrors ASHRAE 188. While not legally binding, it is frequently referenced by surveyors and inspectors for disease control best practices. It helps facilities:

• Identify areas where Legionella species can grow
• Determine engineering controls and monitoring strategies
• Create corrective action plans when tests show contamination
• Design training and documentation practices for staff

Using the toolkit doesn’t replace full compliance, but it shows a good-faith effort and aligns with most public health guidance documents in the U.S.

State and Local Mandates

Several states and cities – especially those with large healthcare or hospitality sectors – have adopted their own rules for legionella testing and management. For example:

• New York City requires routine legionella testing and documentation for cooling towers
• Illinois mandates risk assessments and mitigation plans for hospitals and skilled nursing facilities
• California includes Legionella-specific protocols in some Environmental Protection Agency enforcement actions

What matters is not just whether a facility has controls – but whether it can show inspectors exactly what it’s doing to monitor water quality, reduce risk, and respond to positive tests.

Legal Liability and Case Trends

Beyond regulation, legal liability has grown significantly. In recent years, high-profile legionella growth and legionnaires disease lawsuits have led to:

• Multi-million dollar settlements for residential healthcare facilities
• Class action suits involving airborne water droplets from contaminated cooling towers
• Court rulings against building owners who failed to maintain or perform appropriate legionella testing

Plaintiff arguments often hinge on:

• The absence of a documented water management program
• Failure to conduct periodic testing
• Ignoring prior odor, discoloration, or temperature complaints
• Inadequate engineering controls or preventive actions

Facilities of all types – especially those with at-risk populations – are now expected to take proactive measures and keep clear records. A “wait and see” approach no longer provides legal protection.

For a full breakdown of legal trends and guidance by state, see our Legionella Lawsuits Case Law Review.

Legionella Testing: Methods, Frequency, and Action Plans

Legionella testing is a critical component of any Legionella monitoring strategy. Whether required by regulation, internal risk policy, or as part of a CMS-compliant water management program, legionella testing tells you whether control measures are working – and where intervention may be needed.

But not all Legionella testing is created equal. Facility teams need to understand how different test methods work, what each test reveals, and how often to sample to stay ahead of a developing problem.

What types of tests are available?

There are three common legionella testing methods used today to detect Legionella bacteria in building water systems:

1. Culture Testing (ISO 11731 or CDC Method)

This is the gold standard used in regulatory environments. A water sample is filtered, placed on a growth medium, and incubated for up to 10 days. Colonies are then counted to quantify the presence of Legionella pneumophila or other Legionella species.

• Pros: Quantitative; detects live bacteria; widely accepted
• Cons: Long turnaround time; may underestimate due to stressed or damaged cells

2. Polymerase Chain Reaction (PCR)

PCR testing detects genetic material (DNA) from Legionella species. It’s faster than culture testing and can detect both live and dead bacteria.

• Pros: Results within 1-2 days; very sensitive
• Cons: May detect dead bacteria; less accepted in some regulatory contexts

3. Rapid Tests (Immunoassay or Lateral Flow)

Used for onsite spot checks, rapid test kits detect antigens of Legionella species in water samples. Results are available in 25-45 minutes.

• Pros: Fast; ideal for preliminary screening
• Cons: Less sensitive; should not replace lab analysis for compliance testing

Some facilities use a hybrid approach – culture testing for documentation and compliance, with PCR or rapid testing for routine monitoring between full lab submissions.

Where should samples be collected?

Sample collection should be driven by a facility’s risk assessment and water system layout. Common sampling points include:

• Hot water return loops
• Cold water storage tanks
• Showerheads and faucets in patient or resident rooms
• Ice machines and therapy spas
• Cooling tower sumps and drift eliminators
• Decorative fountains or humidifiers
• Any other potable water systems

The entire building water system should be considered, especially in large or older buildings. Sample collection should focus on high-risk zones where stagnant water, warm temperatures, or inadequate disinfectant residuals may be present.

In cooling tower systems, see EAI’s Guide to Legionella Detection in Cooling Towers for sampling protocols and response thresholds.

How often should testing be done?

Testing frequency depends on:

• Facility type: Healthcare facilities often test quarterly or monthly; hotels or offices may test annually
• System complexity: Buildings with multiple towers, large loops, or warm water features require more frequent legionella testing
• Past history: If Legionella contamination has been found previously, more frequent legionella testing is required until corrective actions prove effective
• Regulatory expectations: Some jurisdictions (e.g., New York) mandate testing frequencies for specific system types

Most water management programs include routine legionella testing at minimum once per year, with quarterly or semi-annual intervals for higher-risk systems.

What are acceptable test results?

There is no universal “safe” level of Legionella, but many facilities use the following reference thresholds:

• <10 CFU/mL (colony forming units): Generally acceptable
• 10-100 CFU/mL: Watch closely; evaluate control measures
• >100 CFU/mL: Investigate immediately and consider remediation
• >1,000 CFU/mL: Take immediate corrective action, including disinfection, retesting, and system review

Some systems aim for zero detection, particularly in healthcare or residential care settings. However, achieving absolute zero in complex systems isn’t always practical – what matters is consistent monitoring and trend analysis over time.

How to respond to positive results

If Legionella culture or PCR results indicate elevated counts, response should include:

• Reviewing system maps to check for missed or stagnant areas
• Verifying temperature, flow, and disinfectant control data
• Flushing affected zones
• Adding temporary or permanent chemical treatment (e.g., chlorine dioxide or monochloramine)
• Retesting 7-10 days after remediation to verify success

Document every action taken, even for low-level positives. Infection caused by unaddressed contamination, especially in residential healthcare facilities, is a serious liability and may trigger regulatory intervention.

Cooling Towers: A High-Risk Zone for Legionella Growth and Exposure

Among all building water systems, cooling towers are among the most significant sources of Legionella risk. These systems – used to remove heat from HVAC, refrigeration, and industrial processes – circulate large volumes of warm water in open-air conditions. That makes them ideal for aerosol formation and, if not maintained properly, for harboring and distributing Legionella bacteria.

Outbreak data over the past decade shows that cooling towers have been implicated in multiple large-scale incidents, some involving dozens or even hundreds of cases of Legionnaires’ disease traced back to contaminated plumes.

Why cooling towers are such a risk

Unlike closed-loop systems, cooling towers are designed to release airborne water droplets as part of normal operation. These droplets – known as drift – can travel hundreds of feet in the right conditions. If the tower water contains Legionella species such as pneumophila, those droplets can carry bacteria into nearby buildings, public walkways, potable water systems, or air intake systems.

Conditions that promote growth in cooling towers include:

• Warm water temperatures (77°F to 113°F)
• Nutrient buildup from organic debris, dust, or process water contaminants
• Stagnant zones inside basin corners or sump areas
• Scale and corrosion that support biofilm formation
• Inadequate biocide dosing or poor biofilm penetration
• Irregular maintenance schedules or chemical feed interruptions

The combination of water exposure, drift, and airborne transmission enable increased risk in towers especially sensitive to even short-term lapses in water treatment programs.

Regulatory pressure is increasing

In response to past outbreaks, several cities and states have imposed strict cooling tower oversight and water treatment requirements. New York City, for example, requires building owners to register towers, conduct routine Legionella testing, and follow specific cleaning and disinfection schedules.

Facilities may be required to:

• Perform risk assessments to identify tower vulnerabilities
• Test tower water quarterly or more often
• Maintain a documented water management program
• Conduct remedial cleaning following positive results or test failures
• Keep service logs and testing results available for inspection

Cooling tower operators who fail to comply can face fines, shutdowns, or even liability if a disease control and prevention investigation links the system to an outbreak.

Learn more about site-specific planning in our guide to Legionella Risk Assessments in Cooling Towers.

Monitoring and controlling Legionella in cooling towers

Effective Legionella control in tower systems requires a combination of proactive monitoring, biocide programs, and mechanical design best practices.

Key control measures include:

• Routine testing for Legionella, total bacteria, and biofilm presence
• Continuous biocide feed, supported by oxidizers and dispersants
• Manual or automated blowdown to reduce water quality issues and scale buildup
• Mechanical maintenance, including drift eliminator inspection and sump cleaning
• Regular inspections of nozzles, fill material, and water distribution
• Temperature and pH tracking to ensure optimal disinfectant activity

In systems where control is inconsistent or drift emissions are high, vapor-phase odor or pathogen controls may also be added to protect surrounding public health.

For implementation support, see EAI’s step-by-step resource on Preventing Legionella in Cooling Towers.

Documentation and audit readiness

Cooling towers are frequently included in routine testing audits during health inspections or complaint investigations. Operators must be ready to provide:

• Test results
• Biocide feed records
• Tower inspection logs
• Cleaning schedules
• Water management program documentation
• Corrective actions taken following any Legionella contamination

Even if your local authority doesn’t currently enforce these requirements, it’s becoming standard practice across the U.S. to treat cooling towers as a standalone risk requiring explicit management.

For state-by-state regulatory insight and what to expect if an outbreak occurs near your facility, refer to EAI’s page on Cooling Tower Liability and Legionella Outbreaks.

Designing and Implementing a Water Management Program (WMP)

The most effective way to prevent Legionella-related illness, and the first step that EAI recommends its clients take, is to build a program that identifies risk in managing legionella, monitors it routinely, and responds before problems grow. That’s the role of a water management program – a documented, structured plan that governs how your facility tracks and controls Legionella growth, and addresses legionella across all relevant water systems as required.

Whether your building is a hospital, university, manufacturing facility, or office complex, a well-designed WMP is your first line of defense. It also happens to be the first thing regulators and legal investigators ask to see when infection prevention efforts are questioned.

What is a water management program?

A water management program is a written, facility-specific plan that:

• Identifies areas in the water system where Legionella bacteria could grow
• Establishes control measures to prevent or mitigate those risks
• Sets acceptable control limits (e.g., temperature, disinfectant levels)
• Details monitoring procedures to verify system performance
• Describes corrective actions to take when limits are exceeded
• Documents routine tasks, roles, and communication pathways

This framework mirrors the expectations laid out in ASHRAE 188 and the CDC Water Management Toolkit – two resources that form the basis for many audits and inspections across the U.S.

Who’s responsible for it?

WMPs must assign responsibility to a qualified team. This team typically includes:

• Facility managers or building engineers familiar with system design
• Environmental health and safety officers or infection control staff
• Outside consultants or water treatment providers
• Maintenance personnel who conduct sampling, testing, and flushing
• Senior management responsible for budget and policy decisions

Each team member’s role should be clearly defined in the plan – including who reviews data, who authorizes changes, and who manages documentation.

Identifying hazardous conditions

Your WMP should begin with a system risk assessment. That means mapping out:

• All water systems (hot, cold, cooling towers, decorative fountains, spas)
• Key control points (e.g., mixing valves, storage tanks, heat exchangers)
• Known risk factors such as stagnant water, warm temperatures, or cross-connections
• Areas serving compromised immune systems, such as patient rooms or dialysis units

This map should highlight where hazardous conditions may exist – especially those that could allow bacterial growth or airborne water droplets to expose occupants.

Your plan should be a living document, updated when:

• New plumbing or equipment is installed
• Building usage changes significantly
• Legionella is detected during routine testing
• A maintenance failure results in unwanted odors or contamination

Control measures and monitoring strategies

Control measures are actions your team takes to keep water systems within acceptable limits. These may include:

• Temperature control for hot water delivery and cold water storage
• Disinfectant residuals, such as chlorine or monochloramine dosing
• Flushing schedules for low-use outlets or seasonal buildings
• Inspection and maintenance of cooling towers and storage tanks
• Use of engineering controls to limit aerosolization or flow stagnation

Each control measure must have a clearly defined control limit – for example, keeping cold water below 68°F (20°C), or maintaining free chlorine above 0.5 mg/L.

Once limits are defined, you’ll need to establish monitoring protocols. These may include:

• Logging temperatures weekly at distal outlets
• Measuring disinfectant levels at sampling points
• Recording pressure drops or flow rate fluctuations
• Verifying sample collection for legionella testing at high-risk zones

Corrective actions and response planning

Your WMP should clearly define what happens when a control limit is breached or Legionella contamination is confirmed. That may include:

• Flushing affected areas
• Cleaning or disinfecting equipment
• Increasing chemical feed rates
• Temporarily closing part of the system
• Retesting to confirm effectiveness

Each corrective action should include who is responsible, what documentation is needed, and how long follow-up should continue.

In the event of a positive test, fast, documented action is your best defense against both health risk and legal exposure.

Keeping the WMP usable and audit-ready

A WMP isn’t a one-time project – it’s a management tool. Your team should:

• Review the plan annually
• Conduct environmental assessment walk-throughs of plumbing
• Track action items and testing results over time
• Keep the plan readily available for inspections or emergencies

Facilities that maintain a current, practical WMP not only lower risk – they also build resilience. A clean, well-used WMP can often make the difference between a minor response and a major investigation.

Long-Term Legionella Monitoring and System Resilience

A water management program is only as effective as its follow-through. Once Legionella control measures are in place, ongoing verification becomes the core of risk management. That includes testing, recordkeeping, response tracking, and periodic reassessment. These steps ensure that what’s documented on paper reflects what’s happening in the building’s water systems – and that the system adapts to operational change over time.

Too often, building operators assume that implementing a water management program means they’ve “checked the box.” In reality, Legionella monitoring is a continuous process, just as water flows – and even the best-designed plans require tuning over time.

Setting a routine testing schedule

Routine testing isn’t just about compliance – it’s about visibility. Knowing whether Legionella species are present in your system gives you the chance to intervene early and avoid both outbreaks and enforcement actions.

A monitoring schedule should account for:

• System complexity – Larger or older systems should be tested more frequently, especially where pipe dead ends or large loops exist
• Risk category – Healthcare facilities or buildings with high-risk populations (e.g., seniors, immunocompromised individuals) should test quarterly or even monthly
• History of contamination – Sites with previous positives should continue to test frequently for at least a year after remediation
• Cooling tower seasonality – Towers should be tested more often during warmer months or when operational demand increases

Even if your local health department doesn’t mandate testing intervals or chlorine treatment methods, a documented testing plan strengthens your defense during audits, inspections, or legal investigations.

Using monitoring data effectively

Data collected from sample collection, temperature tracking, and residual disinfectant logs shouldn’t sit in a folder. They should be used to spot trends and identify emerging problems – before they escalate.

Facilities should review:

• Repeated marginal test results in the same location
• Fluctuations in warm temperatures, water pressure, or chlorine levels in specific loops
• Outlets that consistently show low flow or high turbidity
• Tower drift issues tied to visible buildup, odor, or biofilm

This review process should be built into monthly or quarterly team meetings and feed into the WMP review cycle.

Reassessing risk as your building evolves

Your building’s water system is dynamic. Changes in usage, occupancy, or plumbing heating layout can introduce new risk factors that may go undetected if the WMP isn’t updated. Common events that warrant a reassessment include:

• Renovations or re-piping projects
• Expansion of building wings or new equipment installations
• Changes in water source or city water chemistry
• Extended shutdowns or seasonal closures
• Equipment failures (e.g., heat exchangers, softeners, filters) that disrupt treatment consistency

Any of these can create hazardous conditions or reduce the effectiveness of your control measures. That’s why most facility teams reassess their WMP annually – even if no issues have been detected.

Documentation: Your strongest defense

When disease control and prevention authorities respond to a Legionella case or complaint, the first thing they’ll ask for is documentation. Even a well-managed system may experience sporadic positives – but the ability to show a clean record of:

• Testing
• Control limit monitoring
• Corrective actions
• Risk reviews
• Team responsibilities
• Training and logs

…can often mean the difference between a temporary adjustment and a major investigation or citation.

Documentation should be:

• Centralized – Digital systems or shared drive folders allow for better continuity when team roles change
• Accessible – Keep records available for regulators, not buried in binders
• Current – Don’t let annual review dates lapse; it weakens your program credibility

Supporting sustainability alongside safety

Legionella control isn’t separate from your building’s sustainability goals – it complements them. Properly maintained systems use less energy, reduce scale formation, and minimize the need for aggressive chemical shock (chlorine treatment) or emergency disinfection.

For example:

• Maintaining correct temperatures helps both safety and energy efficiency
• Preventing scale and corrosion improves heat transfer and extends equipment life
• Targeted disinfectant use limits over-dosing, reducing chemical waste

When water systems are optimized for health, they also tend to operate more efficiently – reducing cost, risk, and environmental impact.

Supporting Smarter Legionella Monitoring

Legionella control isn’t just a regulatory requirement – it’s a responsibility tied to public health disease control and prevention. As systems grow more complex, and as occupant expectations and legal scrutiny increase, facility managers can’t afford to treat water systems as passive infrastructure. Monitoring has to be active, informed, and supported.

That’s where external support often plays a role.

At EAI, we assist operators with:

• Site-specific risk assessments
• Legionella sampling strategies and routine testing plans
• Temperature and disinfectant tracking
• Cooling tower treatment and monitoring systems
• Compliance alignment with ASHRAE 188, CMS, and CDC toolkits
• Documentation and response planning

We don’t just hand over a binder – we work with your team to make sure the plan lives in your system, not just on your shelf.

If you’re implementing a new water management program, responding to a Legionella culture positive test, or preparing for a compliance audit, our team is available to help facility managers design, validate, or optimize your system.

Explore EAI’s Legionella Resources

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