Safety Briefing — OSHA Legionella control expectations for cooling towers
OSHA’s Technical Manual Section III, Chapter 7 and 2023 enforcement guidance reinforce that employers must run documented cooling tower water management plans, biocide treatment, and incident response under the General Duty Clause.
Executive briefing: OSHA uses the General Duty Clause and guidance in its Technical Manual Section III, Chapter 7 (Legionellosis) to evaluate cooling tower programs during inspections. The 2023 revision emphasises written water management plans aligned with ASHRAE 188, routine biocide treatment, drift eliminators, and immediate response protocols when Legionella is detected. Employers with building cooling towers or evaporative condensers should expect compliance officers to request sampling records, contractor qualifications, and corrective-action logs.
Key obligations
- Written water management plan. Define tower schematics, control limits for biocide, bleed-off, and conductivity, plus verification and validation steps consistent with ASHRAE 188.
- Routine monitoring and treatment. Maintain documented biocide schedules, cycle-of-concentration controls, drift eliminator maintenance, and quarterly Legionella sampling when required by risk assessments.
- Worker protection. Provide PPE and training for employees performing chemical handling, sampling, or cleaning; control exposure to aerosols during shutdown/start-up and during remediation.
- Incident response. Positive Legionella findings should trigger immediate disinfection, retesting, notification of affected workers, and communication with local health authorities where mandated.
Implementation timeline
- Active enforcement. OSHA applies the Legionellosis chapter during general industry inspections today, particularly in healthcare, hospitality, and multi-tenant offices.
- Seasonal risk windows. Pre-cooling season start-up and mid-summer checks are focal points; inspectors expect evidence of commissioning cleaning and ongoing drift control.
- Contractor oversight. Service contracts should embed scope for sampling, chemical treatment, and emergency response with clear documentation handback to the employer of record.
Program actions
- Update plans. Refresh water management plans with tower diagrams, control limits, sampling points, and corrective actions; link to SDS and lockout/tagout procedures.
- Audit records. Verify biocide logs, sampling results, and certificate-of-analysis documents are complete and retrievable for OSHA inspections.
- Train teams. Provide annual training on Legionella hazards, PPE, and spill response for maintenance staff and contractors.
- Coordinate with health authorities. Establish notification thresholds and contacts for local health departments to accelerate incident reporting.
Sources
- OSHA Technical Manual Section III, Chapter 7: Legionellosis
- OSHA Fact Sheet: Legionnaires’ Disease
- ASHRAE 188-2021 Legionellosis: Risk Management for Building Water Systems
Zeph Tech helps facility teams operationalize OSHA’s expectations for cooling towers through documented water management plans and training.
