How can you prevent Legionella in your building’s internal plumbing system?

To prevent the growth of bacteria like Legionella in your plumbing, there are actions that you can take that vary in complexity depending on what type of water system you have. Although the risk is low for a healthy person to contract Legionnaires’ Disease (in the home), there are simple precautions you can take to prevent the growth of Legionella. 


Showerheads and Faucets

Clean showerheads and faucet aerators at least four times per year to minimize the growth of the Legionella bacteria.

Clean them more often if your home has high risk occupants or if there is build-up of minerals or slimy film.


Water Heaters

Setting the Water Heater Temperature

Keeping your home’s water heater at 140°F will reduce the growth of Legionella.

However, to reduce the risk of scalding, the temperature of the water leaving the showerhead or faucet should be no higher than 120°F.

Gas and Electric Water Heaters

Homes with high risk individuals may consider installing tankless water system, set at 122°F, which both reduces the risk of scalding and prevents the growth of Legionella bacteria.


Flushing the Water Heater

Emptying and refilling (flushing) the hot water tank is a good practice.

If you are not completely familiar and comfortable with this task you could contact a licensed or qualified plumber to do it for you.

Water Filters

Water filters that are installed at any faucet, also called point-of-use (POU) filters, should be changed according to the manufacturer’s recommendations because if not, Legionella bacteria can grow on the filters and lower the water quality.



Humidifiers create fine mists of water that can host and transport Legionella bacteria into your lungs, if they are not cleaned properly. Humidifiers can be complex appliances, so it is best to follow the manufacturer or the supplier’s instructions for cleaning and maintaining them.


Hot Tubs/Jacuzzi®s/Spas, and Pools

Legionella grow best in warm water, like the water temperatures in hot tubs and spas. Warm temperatures also make it hard to keep disinfectants at the levels needed to kill germs like Legionella. Therefore, hot tubs, spas and pools should be periodically inspected to ensure they are operating properly and adequately cleaned. Disinfectant levels and the pH should be checked regularly. 

Hot Tubs


For more information about Legionnaires’ disease or the ecology of the Legionella bacteria, check out the CDC website.