Is it possible to ensure that there is no risk of Legionnaires’ disease during Hilo peak demand events?

Only a Legionella-proof water heater would guarantee no risk of contracting legionellosis, but no such device is currently available on the Québec market.

Legionella is a bacterium naturally found in very low concentrations in fresh water. However, it can grow in artificial water systems where water is stagnant and warm, like spas, water heaters and cooling towers.

Legionella reproduces in stagnant water between 32°C and 45°C. Infection can occur by inhaling fine droplets of contaminated water. The bacteria can thrive at the bottom of a water heater tank where the temperature often remains lukewarm, especially in older tanks.

Regardless of peak demand events (formerly known as “Hilo challenges”), there is always a risk of Legionnaires’ disease, particularly when hot water runs out during a shower. Infection can occur by inhaling contaminated microdroplets.

The goal of peak demand events is to shift electricity use, especially for hot water. The temperature probe on the Hilo solution helps reduce the risk of running out of hot water and, by the same token, exposure to lukewarm water at the bottom of the tank. If the probe detects lukewarm water at the top of the tank during a peak demand event, the water heater automatically starts to heat the water again.

Some simple precautions, such as taking shorter showers to avoid drawing lukewarm water from the bottom of the tank, can help protect against legionellosis year-round.

According to the National Plumbing Code, the temperature inside a water heater should not fall below 60°C. It is also recommended not to exceed this temperature to limit the risk of scalding.

For more information and recommendations to prevent legionellosis, or Legionnaires’ disease, go to: https://www.quebec.ca/en/health/health-issues/a-z/legionellosis