Legionella bacteria growth is a common but serious water facility management concern. There are several prevention methods for keeping this deadly bacteria out of your water system, and strategic water temperature adjustment is one of them. It is important to remember that the best Legionella prevention plans use temperature as one of many protective measures.
Before you attempt this method, it is recommended that you learn as much as possible about the complexities of water temperature and its impact on the proliferation and life cycle of Legionella bacteria.
What Happens When The Water Is Cold?
Legionella bacteria, like any living organism, have a temperature preference. When temperatures are too cold, the bacteria go dormant but do not die. They become active again when temperatures rise.
The number to keep in mind is 20 degrees Celsius (68 degrees Fahrenheit). Legionella turns dormant when exposed to temperatures below 68 degrees Fahrenheit. While this prevents the bacteria from further reproducing, your system may still contain a heavy bacterial load if no other measures are taken.
Legionella bacteria becomes active and begins to propagate when swimming in water temperatures between 68 and 113 degrees Fahrenheit the ideal temperature range for their growth.
What Happens When The Water Is Hot?
If Legionella bacteria thrive at temperatures between 68 and 113 degrees Fahrenheit (20 to 40 degrees Celsius), what happens to them at higher temperatures? Unlike cold water, which only causes the bacteria to go dormant, hot enough water can kill Legionella.
Legionella commence a slow death at 122 degrees Fahrenheit (50C). Increase the temperature to 140F (60C) and most if not all of the bacteria will die within two minutes. Some bacteria may survive. For this reason, a temperature of 70C (158F) is recommended because it will instantly kill all Legionella bacteria upon contact.
Can I Keep My Facility’s Water At the Right Temperature All The Time?
If 158 degrees Fahrenheit is enough to kill all remaining traces of Legionella bacteria, why not just keep your facility’s water that hot all the time? The reasons should be apparent. Maintaining a steady water temperature of 158 degrees could be expensive.
Water this hot also scalds human skin and can cause third-degree burns in two seconds or fewer. This is a health risk that most local and state regulations have prohibited for potable water supplies. Likewise, consistently frigid water temperatures could interfere with machinery or reduce the efficiency of your equipment.
Managing Legionella Bacteria Growth Through Water Temperature
Using water temperature to manage Legionella risk will require you to install a system that can accommodate changing the temperature of the water before it reaches its use point.
In other words, supply water that comes back into the heating system should be boosted to 158 degrees. You must heat the water that you intend to use before it ever gets to the point where people could come in contact with it in order to prevent the potential for injury.
Reaching 158 degrees will kill Legionella. After this, the water should be disinfected due to the temperature, but it cannot be sent into the system while hot.
Next, the system can mix disinfected cool water into the hot water, reducing its temperature. Now that the water has reached a safe temperature and all potential Legionella bacteria have been killed, it can be distributed throughout the system safely.
This ensures that end users are not receiving scalding water and that your energy costs are kept to a minimum through strategic use of hot water. However, it is important to remember that your cool water must be disinfected; otherwise, you are reintroducing contaminated water to your clean water.
The ideal way to achieve this is for some water to be disinfected with heat and then reserved for this purpose. The best method and layout for your water system will depend on a number of factors. You don’t have to develop a Legionella strategy on your own; an expert can help you create a custom plan.
Trust The Experts To Help You Develop A Legionella Control and Prevention Plan
Whether you’ve confirmed a Legionella problem in your water system or you’re ready to take new preventative measures, do not hesitate to ask the experts for help. The professionals at Legionella Compliance Solutions would be happy to craft a custom plan for your facility.
Legionella control is about more than public safety – it also factors into your facility’s compliance requirements, and navigating these rules can be overwhelming on your own. Reach out to learn more or to schedule an appointment to get started.