Legionella Overview

A type of Legionella bacteria

Legionella bacteria

Legionnaires’ disease has been on the news lately due to an outbreak in the Bronx section of NYC. There have been over a hundred people affected and over 12 deaths and the numbers continue to rise. Are you at risk? The following conditions cause the Legionella bacteria to thrive:

1) Stagnation

2) In hot systems, water temperatures below124 degrees Fahrenheit (°F) (51.1 degrees Celsius (°C)) or higher are necessary to inhibit Legionella growth.

In cold water systems (temperature at 67°F (19.4°C) or lower) tend to be too cold to foster growth of Legionella. Nonetheless, cold water in piping and fixtures can reach ambient environmental temperatures exceeding 68°F (20°C) during prolonged periods of low flow or non-use. Use of piping system insulation, automatic drain devices, and recirculation to limit the rate and duration of an increase in cold water temperature in combination with appropriate biocide levels can be effective at preventing Legionella growth.

3) pH between 5.0 and 8.5

4) The presence of microorganisms that promote growth such as algae and bacteria.

The water systems that frequently provide the optimal growth scenario are the following:  (according to OSHA website)

1) Cooling towers, evaporative condensers and fluid coolers that use water evaporation to reject heat. These are mainly used in commercial air conditioning systems.

2) Domestic hot water heaters with that operate below 140 degrees.

3) Poorly maintained humidifiers and decorative fountains that create a water spray and use water at temperatures favorable to growth

4) Spas and whirlpools with aeration

5) Dental water lines

Inspections should be performed quarterly through one of our inspection programs. To find out more information and how we can help with a qualified evaluation and testing program contact us.