Queensland Government
Department of Housing and Public Works

Water is an important natural resource and should be used with care and consideration for our environment. Care should be taken when using water around the home. People are generally aware of the hazards associated with boiling water and slipping on wet floors, but in rare cases, water also has the potential to cause illness.

Bacteria in the water supply

Although drinking water is usually treated to make it safe, bacteria may still be present at very low levels. These bacteria may only become a problem if they are allowed to multiply to levels that can cause illness.

The main places where bacteria may multiply in your home's water system are:

  • in the hot water system, if it is regularly turned off or if the water temperature is set too low; and
  • in water lines or outlets that are seldom used.

Warning stickers

The department installs warning stickers on every electric hot water system as part of its annual property inspections or during other visits to the property. The sticker provides advice on the safe use of electric hot water systems to help you reduce the risk of dangerous levels of bacteria multiplying in your home's hot water system. Gas hot water systems tend to be more difficult to adjust and are less of a concern in this regard.

How can I prevent bacteria multiplying in my household water?

  • Do not interfere with the normal operation of your hot water system. Hot water systems are designed to operate without any adjustment. The temperature is preset by the manufacturer and should not be turned down unless by a qualified tradesperson. The system should remain on at all times to ensure that the water is kept hot enough to kill any bacteria present.
  • Try to use each tap or water outlet inside and outside the home regularly. Simply turn them on at least once every two months and allow the water to flow through. This cleans out any still water that may have been in the pipe. Still water in pipes alone is not sufficient for dangerous bacteria to be present. A number of other factors have to occur as well. However, ensuring you regularly clear the pipes will minimise any health risk.

I only have cold water connected to my washing machine. There is also a hot water outlet in the laundry – what should I do?

Try to run the hot water tap for a minute or so every two months. This will allow the water resting in the pipe to be replaced with clean water. Use a bucket to collect this water if the tap is not connected to your washing machine. You will only need to run the tap until the bucket is about half full. If the water is hot, wait until it has cooled before using it to water the garden.

What if I switch off the hot water to save electricity?

Unless you are going away for an extended period (for example, three months), the hot water system should not be switched off. When you return, ensure the unit has reached its full temperature before using the hot water.

If you are going to be away from your home for an extended period, discuss what to do with the hot water system with your nearest Housing Service Centre when you discuss your absence.

Sometimes I switch off the hot water system because the water is so hot I am afraid it will scald or burn someone.

Do not adjust the water temperature below 60 degrees Celsius and do not turn the system off. If you have young children or adults with illness or infirmity living in your home and are concerned about the water temperature, talk to your nearest Housing Service Centre. The department will install tempering valves to all bathroom outlets to ensure that the temperature does not exceed 50 degrees Celsius.  The department can also install tempering valves on some additional water outlets or on your hot water system.

I like the temperature of my water to be hot – do I have to have a tempering device?

It is a statutory requirement that tempering valves are installed to all bathroom outlets. Tempering valves make sure that hot water temperature does not exceed approximately 50 degrees Celsius. This reduces the risk of scalding from hot water. These are fitted by the department during bathroom upgrades or major replacement of water devices.