Legionella bacteria, the cause of Legionnaires’ disease, is a major concern for building owners, facility managers, and public health officials. This potentially deadly pathogen thrives in water systems and can spread through mists, vapors, or aerosols.
While not yet regulated as a drinking water contaminant under federal law, many states and cities have enacted specific Legionella testing requirements, especially for cooling towers and healthcare water systems.
For a full breakdown of sampling methods and lab processes, see our legionella testing services.
Understanding where Legionella testing is required and why it matters can help you protect occupants, reduce liability, and ensure regulatory compliance.
Is Legionella Regulated at the Federal Level?
No, Legionella is not regulated under the EPA’s Safe Drinking Water Act (SDWA) for public water systems.
However, federal agencies play a significant role:
Centers for Medicare & Medicaid Services (CMS): Requires hospitals and long-term care facilities to implement water management programs that address Legionella risks.
Occupational Safety and Health Administration (OSHA): Requires employers to protect workers from exposure to biological hazards, including Legionella, under the General Duty Clause.
ASHRAE Standard 188: While not a law, this widely adopted standard provides a nationally recognized framework for Legionella risk management in building water systems and is often referenced in legal and regulatory mandates.
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Where Is Legionella Testing Regulated at the State and Local Level?
While most U.S. states recommend Legionella testing in high-risk facilities, a growing number now have legal mandates requiring testing, monitoring, and water management plans.
Here are the states and jurisdictions with formal Legionella regulations as of 2025:
New York State (10 NYCRR Part 4)
- Mandatory Legionella culture testing for:
- All cooling towers (initial, seasonal, and every 90 days)
- Healthcare facilities with drinking water systems (routine sampling required)
- Must use ELAP-certified labs, follow strict documentation and disinfection protocols.
- Healthcare providers must report findings and take corrective action for positive results.
New York City (Local Law 77)
- Adds specific mandates to state law:
- Weekly dipslide testing
- Legionella culture testing every 90 days
- Detailed maintenance plans
- Reporting to the NYC Cooling Tower Portal
Learn more about our services for clients across New York, including cooling tower testing and ELAP-certified lab support.
New Jersey (Senate Bill 2188 – Effective Sept 12, 2024)
- One of the most comprehensive statewide requirements:
- Cooling towers, domestic water systems, hotels, nursing homes, and more
- Requires ASHRAE 188-compliant water management plans
- Includes mandatory Legionella testing, documentation, and public notices
- Applies to both new and existing buildings
We serve clients across New Jersey with fully compliant Legionella testing and WMP support.
Illinois (Public Act 1020004)
- Applicable to hospitals and nursing care facilities
- Facilities must:
- Implement water testing policies
- Share Legionella results with the state health department
- Follow risk mitigation strategies if Legionella is detected
Michigan (Code R 325.45303)
- Requires all healthcare facilities to:
- Develop Legionella water management plans
- Include testing and control measures as per ASHRAE 188
Ohio (Licensure Rule 3701-83)
- Applies to licensed residential care and skilled nursing facilities
- Mandates
- Routine assessment of Legionella risk
- Implementation of water safety plans with mitigation controls
Virginia (SB410)
- Applies to public schools
- Requires each district to:
- Develop and implement Legionella water management programs
- Follow ASHRAE 188 guidelines and monitor building water systems
Ensure your property meets all safety standards with our comprehensive testing services
Local Ordinance Highlights
Some city and county governments have passed their own local rules, even where state mandates are not in place:
Garland, TX: Requires annual Legionella testing of cooling towers at apartment complexes.
New Orleans, LA: Mandates water management for cooling towers.
Allegheny County, PA: Issues guidance and requirements for Legionella control in healthcare facilities.
Los Angeles County, CA: Requires Legionella sampling in hospitals and skilled nursing facilities.
Maryland: State and county-level agencies recommend water safety planning, and legislation has been proposed to mandate testing.
Why Knowing the Rules Matters
If you’re managing a commercial building, healthcare facility, educational institution, or residential complex, failing to follow local Legionella regulations can result in:
Health department enforcement or shutdowns
Legal liability if illness is linked to your building
Loss of permits or accreditation
Damaged reputation among tenants, patients, or guests
Even in states without legal mandates, following ASHRAE 188 and working with qualified labs is essential to protect health and reduce risk.
We also assist with regulatory compliance for Legionella testing, documentation, and reporting at both state and federal levels.
Need Help with Legionella Compliance?
Book a risk assessment or testing today with professionals who follow CDC-aligned methods and help ensure you meet the highest standards.
Final Thoughts
The regulatory environment around Legionella is evolving. What was once optional is quickly becoming law in many states. Staying ahead of requirements and implementing a proactive Legionella testing program not only ensures compliance but also protects lives.
If you operate in New York, New Jersey, Illinois, Michigan, Ohio, or Virginia, or in cities like NYC, Garland, or New Orleans, Legionella testing is not optional. And in every other state, it’s a best practice that can shield your facility from preventable risk.