What is Legionella Control?
Key factors in controlling the risk from Legionella and Legionnaire’s Disease include water temperature management, water age, and disinfectant levels.
With regard to water temperature management, Legionella control is more optimal in water systems with the following water temperatures:
- Hot water storage: 140°F minimum
- Hot water distribution 122°F or higher (note that a scald risk is possible, so thermostatic mixer valves need to be fitted as close as possible to outlets)
- Cold water storage: Below 68°F
- Cold water distribution: Below 68°F
For Legionella control to be most effective, a qualified technician should routinely check, inspect and clean the system, in accordance with the Legionella management plan.
In addition, a qualified technician should:
- Identify sentinel outlets, those water outlets closest and farthest away from each storage or source point
- Check the distribution temperatures monthly
- Check the hot water storage cylinder temperatures every month
- Check the cold water tank temperatures every six months or less
Be aware that stagnant (non-moving) water can promote Legionella growth. Therefore, as part of your Legionella control plan, your Legionella technician or engineer should:
- See to the removal dead legs or dead ends in water systems
- Flush out low-use outlets, showers, baths, and faucets at least once per week
- Clean and remove scaling from shower heads and hoses at least every three months
- Clean cold-water storage tanks periodically
- Drain water from hot water cylinders to check for debris or signs of corrosion
In addition, your Legionella control team will design systems to minimize Legionella growth through:
- Keeping water systems as short and direct as possible
- Insulating pipes and tanks correctly
- Sourcing materials that do not encourage the growth of Legionella;
- Fitting tanks with lids and insect screens, as other methods of preventing contamination
- Analyzing water samples for Legionella periodically at frequency dictated by your Legionella control management plan
As warranted, your Legionella control expert may employ other methods to control Legionella include copper and silver treatments, as well as various chemical treatments using Chlorine and Chloramines. Note that all treatments are part an ongoing plan, as proper Legionella control includes continued maintenance and monitoring.
Take our CDC Legionella Risk Assessment to get a quick overview of your risk.