Residential - Tips & tricks - Your water heater and your health

Did you know that in Quebec, 50% of burns for which people are hospitalized are caused by hot water from a faucet? To deal with this public health risk, the Institut national de la santé publique du Québec recommends that hot water temperature be lowered to 49°C (120ºF). If you think this can be achieved by simply setting the water heater thermostat to that temperature, you’d best read on!

First, you should know that the thermostat on the water heater is, according to codes, set in the factory so that a temperature of 60°C (140°F) is maintained. It is generally not recommended that you lower the temperature, because bacteria in water tend to proliferate in a lukewarm milieu.

Although most of these bacteria are not a health risk, one of them – Legionella – causes Legionnaire’s disease, a rare form of pneumonia that particularly affects children, the elderly, and people with a weakened immune system.

Electric water heaters and bacteria
Lowering the temperature of a water heater proves to be even riskier when we learn that studies conducted in Quebec reveal that Legionella bacteria has been detected in almost 25% of electric water heaters, even when the thermostat is set to 60ºC (140ºF). At that temperature, however, the risk is quite low. But it can be a concern given that more than 90% of Quebec households use an electric water heater.

Because of their physical design, electric water heaters seem more prone to contamination than gas or oil-powered heaters. The water temperature in the lower part of the tank is often too low to prevent Legionella bacteria from multiplying. So what are we to do?

For many years, homeowners were encouraged to empty the water tank completely once each year to flush out bacteria and deposits. This practice is not recommended today. Some experts warn against the operation because they say it can exacerbate the contamination. Some plumbers and manufacturers believe that the annual purge shortens the useful lifespan of the devices.

Hydro-Québec, for its part, believes that industry needs to start systematically producing hot water heaters equipped with a mechanism that promotes continuous circulation of water in the tank in order to keep it from stagnating at a temperature that would lead to the growth of bacteria.

The ideal solution
Given the current context, and regardless of what type of water heater you have, the most effective solution involves two steps:

First, to eliminate the risk of Legionella contamination, you should keep the water heater thermostat at 60ºC (140ºF). Second, to reduce the risk of burns caused by hot water from the faucet, it is recommended that you install an anti-burn device on the water heater that will maintain a constant temperature of 49°C (120ºF). A device of this kind ($10 to $50) can also be installed for the shower and kitchen or bathroom faucets.

Lastly, here are a few useful tips to reduce the risk of hot water burns:

  • Always test the temperature of hot water beforehand.
  • Do not change the thermostat setting on the hot water heater.
  • Do not drink hot water from a faucet, instead, heat or boil cold water.
  • Do not turn off the heater fuse if you are going to away for a few days, because the water in the tank must be kept at the recommended temperature at all times.