Legionnaires’ disease has emerged with a spike in cases associated with spa pools over the past months. Since the first report, cases have kept increasing across New Zealand, with recent reports and ESR analysis by Health NZ Te Whatu Ora confirming that individuals who contracted the illness in March 2025 have clear links to contaminated water found in spa pools.
Facility managers and spa pool owners are strongly advised to take swift action to prevent this infectious pneumonia-causing bacteria from spreading.
This blog discusses Legionnaires’ disease, its spread through spa pools, essential prevention strategies, and expert insights.
Understanding Legionnaires’ Disease
Legionnaires’ disease is usually contracted by inhaling aerosolised water droplets that carry Legionella bacteria. The bacteria thrive in hot, stagnant water conditions, and spa pools become breeding grounds if they are not maintained. Legionellosis symptoms include coughing, fevers, muscle aches, and headaches, and the infection can lead to severe respiratory complications if not treated promptly.
How Spa Pools Become a Hotbed for Bacteria
Spa pools are undoubtedly popular and perfect for relaxation. However, if water temperatures and chemical levels are not regulated, they can also promote the growth of harmful bacteria such as Legionella.
Some of the most critical factors that cause contamination are:
- Insufficient disinfectant levels of chemicals such as chlorine allow bacteria to multiply.
- Inadequate water flow in the spa provides areas where bacteria will live.
- Bacteria multiply in water that is warm but not hot enough to kill them, often between 20°C and 50°C.
Facilities and spa pool owners should regularly clean and conduct water quality checks to mitigate these risks
Prevention and Maintenance Strategies
Prevention is a multi-faceted approach, emphasising proper water treatment, frequent maintenance, and strict monitoring.
The following are some of the steps spa pool owners and facility managers should consider:
- Spa parts should be cleaned and disinfected frequently.
- Automated dosing systems may be used to maintain optimum chlorine levels.
- Keeping water temperatures outside the optimal growth range for Legionella can significantly reduce the risk.
- One recommended procedure is heating water to at least 60°C for regular sterilisation.
- Ensuring that water circulates properly prevents the formation of stagnant zones.
- Proper filtration systems are required to ensure clean water.
- Inspections by qualified personnel can aid in detecting and correcting problems before they worsen and involve monitoring for biofilm buildup. This includes checking for biofilm buildup—a slimy layer where bacteria can accumulate.
- Facilities with spa pools should educate users about the significance of hygiene protocols when using the spa pool. Visible signage and public guidelines can reduce risks and possible outbreaks.
While spa pools are the primary concern, the scope of Legionnaires’ disease is broader than recreation and community centres. Hotels, hospitals, and other public spaces with water systems can also be at risk. Hence, the lessons learned in spa management should inform broader public health strategies.
Facility operators should consider the following:
- New water treatment and circulation systems can provide long-term protection.
- Regular training on maintenance routines ensures all personnel are familiar with up-to-date guidelines.
- Possessing and practising a response plan for potential outbreaks can mitigate the risks and ensure quick containment.
By understanding the nature of the disease, detecting factors that help it spread, and putting in place preventative measures, spa pool owners and facility operators can protect public health and avoid outbreaks. As reiterated by health officials and industry leaders, proactive maintenance and ongoing public education are the best defences against disease.
For more information on best practices and expert advice on water system management, contact Amotto Consultancy.
