Using hot water
Around 30% of the energy used by the average household flows into hot water.
Easy savings checklist
Simple changes to the way you use hot water make a difference up over time.
- Wash your clothes in cold water. A hot water wash can use 10 times more electricity than a cold wash.
- Turn off the tap. Fill the sink with hot water instead of leaving the tap running when doing things like shaving.
- Shower rather than bath. It typically uses only half as much water and energy.
- Keep your showers short. Use a timer if you tend to lose track of time.
- Run full loads in the dishwasher and washing machine. Use the eco setting on your dishwasher if it has one.
- Pre-rinse dishes if required, in cold water.
How hot is healthy and safe?
Hot water should be 60°C at the cylinder (to prevent the growth of legionella bacteria) and no more than 55°C at the tap so you don't get burnt. Be extra careful for children. Some cylinder thermostats can only be adjusted by an electrician or plumber.
A list of things to fix, install and improve to save hot water.
- Reduce your shower flow. If your shower fills a 10 litre bucket in less than a minute, it's wasting water. Change your shower head for one with a more efficient flow rate of 9 litres a minute or less. Or, install an inexpensive shower flow restrictor.
- Ease your tap flow. Flow control aerators for taps cost between $10 and $30 and can halve the volume of water you use while still giving good pressure. They’re great for taps over sinks or tubs that aren't regularly filled up, so the water flow volume is less important.
- Fix dripping hot taps. Replace the washer or fitting - a new washer only costs a few dollars.
- Wrap your hot water cylinder and pipe. Pre-2002 electric hot water cylinders aren't well insulated and should have a cylinder wrap. You should also insulate the first metre of hot water pipe coming off your cylinder. Cylinder wraps cost around $60 and pipe insulation is about $5 a metre from hardware stores. Note that you can't put a cylinder wrap on a gas hot water system.
- Maintain your hot water system. This includes gently moving the easing lever of the temperature/pressure relief valve every six months, to prevent it from sticking. Glass-lined water cylinders should have their anode changed every 5 years, more frequently in hard water areas. A plumber can help if you're unsure. Depending on the type of system you have, you may need to do other forms of maintenance - check your manufacturer's instructions.
Less water, more stars
Look for water efficiency labels on dishwashers, washing machines, taps, toilets and showers. More stars means more water efficient – potentially saving thousands of litres a year.
When to switch off
It’s worth switching off your hot water if your house is empty for more than a fortnight. But allow at least 12 hours to reheat before using – water must be hot to kill any legionella bacteria.