Legionella Risk Assessments: The Dangers of Legionella
Legionella is a serious and potentially fatal disease. Simple inhalation of contaminated water aerosols containing Legionella bacterium from contaminated systems can cause infection leading to Legionnaires' disease, a severe form of pneumonia, and Pontiac fever, a milder respiratory infection. Symptoms are very similar to the signs from typical pneumonia, but can turn fatal in under 3 days, which is often too late.
Legionella Testing Frequency Guideline
The Public Works and Government Services Canada has outlined clear guidelines for Legionella testing, in MD 15161 – 2013 Control of Legionella in Mechanical Systems, for Federal Buildings.
3.5.6 Cooling Tower and Evaporative Condenser
While the system is in normal operation, perform monthly Legionella bacteria culture tests to identify total Legionella pneumophila including all serogroups (LPTOT) bacteria levels.
4.4.6 Open Water Systems
While the system is in normal operation, every two months perform Legionella bacteria culture tests to identify total Legionella pneumophila including all serogroups (LPTOT) bacteria levels.
5.3.9 HVAC Systems and Components
While the system is in normal operation, every three months perform Legionella bacteria culture tests on non-steam systems, to identify total Legionella pneumophila including all serogroups (LPTOT) bacteria levels.
6.4.20 Domestic Water Systems and Hot Water Systems
Perform Legionella bacteria culture tests to identify total Legionella pneumophila including all serogroups (LPTOT) bacteria levels
6.4.20.1 Every six months for most remote shower facilities
6.4.20.2 Annually, at the most remote fixture, for systems with a storage temperature below 50° C that serve multiple areas in a building and are not connected to showers