Summer Heat and Hidden Hazards: How Warm Weather Increases the Risk of Legionella in Building Water Systems

As temperatures rise across the country, so do the risks lurking inside building water systems. While summer is often associated with vacations and sunshine, for facility managers and health professionals, it also brings a heightened threat: Legionella bacteria.

Legionella thrives in warm, stagnant water — conditions that are more common in the summer months due to increased heat, decreased water usage in some systems, and inconsistent circulation in plumbing infrastructure. When temperatures soar, so does the chance of Legionella colonizing cooling towers, hot water systems, decorative fountains, and even potable water lines.

Why Summer Is a Breeding Ground for Bacteria

During hot weather:

• Water tanks and pipes absorb ambient heat, raising internal water temperatures into the Legionella danger zone (77°F–113°F).

• Cooling systems are under heavy load, which often means more aerosolization of water — increasing the potential for inhalation of contaminated droplets.

• Vacant rooms or wings in schools, hotels, or healthcare facilities may go unused, creating stagnant zones in plumbing systems — a perfect breeding environment for Legionella.

Even temporary lapses in maintenance or testing during summer vacation periods can open the door to serious contamination.

Real Risks, Real Costs

Legionnaires’ disease spikes in the summer and early fall, with over 70% of U.S. cases reported between June and October, according to the CDC. Outbreaks are not only dangerous but also expensive — leading to patient harm, legal liability, and potential regulatory penalties, especially for hospitals and long-term care facilities.

The Joint Commission's updated water management standards for 2024 underscore the urgency. Facilities must demonstrate active water system risk assessments, testing, and remediation strategies — or risk falling out of compliance.

How Legionella Specialties Can Help

At Legionella Specialties, we work with hospitals, extended care facilities, hotels, and commercial buildings to stay ahead of seasonal threats. Our team offers:

• Proactive water testing and hazard assessments

• Custom water management plans compliant with Joint Commission and ASHRAE 188 standards

• Ongoing monitoring and rapid-response services when heat-related system stress leads to bacterial spikes

Don’t let summer heat catch your facility off guard. Partner with Legionella Specialties to protect your patients, your staff, and your compliance record.