The recent outbreaks of hot water Legionella in Queensland mainly in hospitals is of concern. These, for the most part, were warm water systems 
which are not the same as your home hot water storage tank.
With hot or warm water systems there is always some risk but every system checked in recent weeks by Whywait Plumbing has had hot water temperatures that virtually eliminate all risk. However, there is almost no risk of you or your family contracting Legionella bacteria as a result of it breeding in your home hot water system.
Legionella Transmission Via Hot Water
Legionella transmission is airborne via respiratory droplets containing the bacteria. Warm water and domestic hot water systems that are contaminated will generally see the transmission of the bacteria in a shower that has not been used for a period of time.
Hot Water Preventative Measures For Legionella
Hot water systems should be maintained so that water at the point of use at any tap or outlet is 50°C or more after having been turned on for one minute.
Hot water systems should not be used until they have reached 50°C especially if they have been turned on for any period.
Generally, domestic hot water systems should have a temperature of 60°C or higher in water leaving the hot water storage tank.
DO NOT turn down the thermostat on an electric hot water storage tank to below 60C.
Hot Water Temperature For Preventative Of Legionella
Hot water systems should be maintained so that water at the point of use at any tap has a temperature that affects the survival of Legionella as follows:
- Above 70 °C – Legionella dies almost instantly
- At 60 °C – 90% die in 2 minutes
- At 50 °C – 90% die in 80-124 minutes, depending on strain
- 48 to 50 °C – Can survive but do not multiply
- 32 to 42 °C – Ideal growth range
- 25 to 45 °C – Growth range
- Below 20 °C – Can survive but are dormant, even below freezing
What Is Legionella Bacteria or Legionnaires Disease
What it is:
- Caused by the Legionella bacteria, commonly found in creeks, ponds and soil.
- Rare in people under 20 years, with those over 50 years old who smoke or have a weak immune system particularly susceptible.
Symptoms:
- Non-specific flu-like symptoms including fever, headache and muscle aches, developing within a week of breathing in the bacteria.
- Usually progresses rapidly with pneumonia symptoms, high fever, shortness of breath and chest pain typical.
Treatment:
- A person with the disease usually needs to be admitted to hospital for antibiotic treatment and care.
- Early diagnosis and antibiotic treatment important, and those treated usually begin to improve with three to five days.
Testing Your Storage Tank
For most homes, there is a very little risk of you having hot water legionella occur in your hot water storage tank unless you do really stupid things such as turn off your heating source.
An easy test of the storage temperature is to get a thermometer and test the temperature of your water from the overflow relief valve drain.
If you have any doubts about the temperature in your storage tank contact Whywait Plumbing to organise a service call to check your hot water system.
