Legionella & Fire Sprinkler Systems: What You Need to Know

While Legionella bacteria is a well-known health concern in water systems, it’s important to understand its relevance in fire sprinkler systems. 

What Is Legionella?

Legionella is a naturally occurring bacterium found in freshwater environments. Under certain conditions such as stagnant water, warm temperatures (20–45°C), and the presence of nutrients. It can multiply and pose a risk of Legionnaires’ disease, a serious form of pneumonia transmitted through inhalation of contaminated water droplets.

Is Legionella a Risk in Fire Sprinkler Systems?

In short: not usually. Fire sprinkler systems are classified as low-risk when it comes to Legionella.

• Closed Systems: Most sprinkler systems are sealed and contain stagnant water that is not regularly aerosolised, reducing the chance of airborne transmission.
• Cold Water Storage: Sprinkler systems typically store water below the temperature range that promotes Legionella growth.
• Infrequent Activation: These systems are only activated during fire emergencies or routine testing, limiting exposure opportunities.

When Can Risk Arise?

Although rare, certain conditions can elevate the risk:

• Wet Pipe Systems in Warm Environments: If water sits in pipes exposed to heat, it may reach temperatures conducive to bacterial growth.
• Poor Maintenance: Lack of regular inspections or stagnant water in infrequently tested systems can increase risk.
• System Modifications or Downtime: Changes to pipework or prolonged inactivity may introduce contamination.

How to Minimise Risk

We follow industry best practices to ensure your fire protection system remains safe and compliant:

• Routine Flushing & Testing: Regular maintenance prevents stagnation and ensures water quality.
• Cleaning Protocols: If systems are modified or temporarily decommissioned, proper cleaning and disinfection procedures should be completed before reactivation.

Reassurance You Can Trust

The Health & Safety Executive (HSE) and water hygiene experts agree: fire sprinkler systems are not typically considered a significant source of Legionella risk. With proper design, installation, and maintenance your system remains a reliable safeguard against fire, not a health hazard.