Hot water

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Water heating is the largest source of greenhouse gas emissions from an average Australian home and the second largest segment of household energy use in Australia.

More than half of hot water use is in the bathroom, a third in the laundry and the remainder in the kitchen.

You can get an idea of what hot water costs you with Ausgrid’s Hot Water Calculator

In an apartment building your hot water system could be:

  • A central gas system servicing the entire building, or
  • An individual system servicing only your lot

These are the main steps to consider when addressing hot water energy consumption:

  • Understand the restrictions you may have living in an apartment or townhouse (for individual systems)
  • Get the best hot water system (for individual systems)
  • Install your own solar hot water system (if possible)
  • Get the best tariff for electric systems
  • Use less hot water

Understand the restrictions you may have living in an apartment or townhouse

If your apartment or townhouse has its own hot water system, your options may be limited when it comes to replacing it.

Gas hot water systems are out if you don’t have gas to your apartment. A gas connection may be feasible in some instances. It would most likely impact common property and therefore need to be approved at a general meeting of the owners corporation.

Unless you’re in a townhouse or a top floor apartment, it’s unlikely that solar will be an option. Have a look at the next section if you think it could be.

The condenser for split system heat pumps resides outside. Similarly to split system air conditioners, connections to the indoor unit will probably need to run through common property walls. Permission from the owners corporation and a corresponding bylaw will be needed. You’ll also need to make sure there are no adverse noise impacts for other residents.

Get the best hot water system

It’s wise to plan for your hot water system’s replacement, especially if it is more than ten years old – that way you’re prepared if/when it fails and you’re not under pressure to get a replacement quickly.

Don’t forget to consider running costs as well as the initial purchase price.

There are good government resources to help you choose and install the most appropriate and efficient water hot water system for your household size, water use patterns and climate:

Install your own solar hot water (if possible)

If you’re in a townhouse or top floor unit, you may be able to install a solar hot water system for your own use. However, since the roof space above you is common property you’ll need permission from the owners corporation at a general meeting, and a by-law specifying the terms and conditions on which approval is given.

You can ask for this to be put on to the agenda of the next general meeting of the owners corporation (either the AGM or an EGM). If no meeting is scheduled in a timeframe suitable to you, you can ask for an Extraordinary General Meeting to be called – but you’ll have to cover the costs of that meeting.

You’ll most likely also have to cover the costs of drawing up the necessary by-law – unless there are other interested owners who will share the cost.

We’ve made a list of things that need to be considered in a bylaw governing solar installations for personal use.

Get the best tariff for electric systems

Energy providers in most areas offer special electricity tariffs for water heating.

Discuss your tariff options with your installer before installation begins to understand how different tariffs will affect your running costs and your system’s performance.

Tariffs differ between continuous and off-peak (controlled load) supply, and vary across the states and territories.

More information on Water Heaters – Electricity Costs & Tariffs (Energy Rating)

Use less hot water

Irrespective of the type of hot water system you have, there are many ways to reduce your hot water costs (and your water consumption):

  • Install tap aerators or flow controllers to reduce water flow
  • Install water efficient showerheads to reduce hot & cold water usage
  • Choose water efficient appliances
  • Use cold water when washing your hands, shaving or cleaning your teeth
  • Take shorter showers, ideally 4 minutes or less. Use a shower timer as a reminder
  • Fix leaking taps and appliances. A tap dripping 45 times per minute wastes around 1,000 litres of hot water each month, the equivalent of ten bathtubs.
  • If you have a storage system check the relief valve (a relief valve protects storage water heaters by relieving excess pressure in the system). If a bucket placed under the valve fills in a day, it needs replacement.
  • Wash laundry in cold water
  • Scrape dishes rather than rinse before washing where possible, or use less water (hot & cold) by not rinsing dishes under running water. If you must rinse, rinse in cold water
  • Keep mixer taps in the cold water position when hot water is not required. It only takes a slight movement away from ‘cold’ to allow for the flow of hot water through the valve. You may not feel any measurable increase in heat from the water, however hot water is being fed into the flow of water and you’re being charged. A mixer tap handle should always pushed hard against the cold side.
  • Insulate any exposed hot water pipes
  • Continuous flow (instantaneous) HWSs should be set to no more than 50°C. Any higher temperature means that energy is used unnecessarily
  • Set the thermostat of your storage HWS to above 60°C to prevent growth of harmful Legionella bacteria. Too high a temperature means that energy is used unnecessarily
  • Maintain the system and have it serviced according to manufacturer’s instructions
  • Turn off your hot water system when going on holidays. When you return ensure that the water is heated and stored above 600C for at least 35 minutes before use. This will kill any bacteria that may have grown. It could take several hours for the water to heat above 600C.


Last Updated: 
Tue 08/03/2016

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