Simple ways to save on hot water

Whatever hot water system you have, there are some easy ways to reduce your energy use without impacting on your lifestyle.

Streamline your system

There are some simple things you can do to cut your energy and water waste, and make your existing hot water system as efficient as possible.

• Wrap your hot water cylinder and pipes. Hold the heat in by wrapping your electric hot water cylinder (you can't put a cylinder wrap on a gas hot water system) and insulating your hot water pipes. Wraps cost around $60 and pipe insulation is about $5 a metre from hardware stores. For an older (pre-1987) cylinder and pipes, you could save up to $150 a year.
• Fix dripping hot taps. These can waste up to 200 litres of water every day, or hundreds of dollars of energy each year. Replace the washer or fitting - a new washer only costs a few dollars.
• Check your shower flow. Around 80% of a home's hot water is used in showers. If your shower fills a 10 litre bucket in less than a minute at normal showering temperatures, install an efficient shower head - you'll get a good shower and it could save you a lot. If it filled in 50 seconds you could save $200 each year; 40 seconds you could save $390 each year; 30 seconds you could save $720 each year.^[1] Get a shower head with a flow rate of 9 litres a minute or less - you can compare the efficiency of new showerheads at www.waterrating.gov.au.
• Ease your faucet flow. Where the volume of water doesn't matter - like sinks or tubs that aren't regularly filled up - flow control aerators for faucets cost around $2 and can halve the volume of water used while still giving good pressure.
• Check your hot water temperature. It should not be more than 55° Celsius at the tap so it is low enough not to burn, and it must be 60° Celsius at the cylinder to prevent the growth of Legionella bacteria. Don't have the thermostat on your hot water system higher than necessary - an extra 10° Celsius could cost you $20 to $30 a year. You might not have noticed it's too high if, as with most modern systems, yours has a tempering valve to add cold water to the hot water coming from your cylinder to prevent scalding. And without a tempering valve, a hot water thermostat set higher than necessary is a scalding risk. You may need an electrician or plumber to adjust your thermostat.
• Maintain your hot water system regularly. This includes gently moving the easing lever of the temperature/pressure relief valve (if you have one) every six months. Glass-lined water cylinders should have their anode changed every five years, more frequently in hard water areas. A plumber can help you do these things if you're unsure. Depending on the type of system you have, further maintenance actions may be required - check your manufacturer's instructions.

Easy hot water habits

With some easy, everyday hot water habits you can cut your energy use - and your environmental impacts - even more.

• Use cold water for washing your clothes. At four loads a week, this could save you around $50 - $75 each year.^[2]
• Rinse dishes with cold rather than hot water.
• Only run the dishwasher when it is fully loaded, and then on an ‘eco', ‘half load' or ‘fast' wash setting if available.
• Fill the sink with hot water rather than leaving the hot water running when doing certain tasks like shaving.
• Shower rather than bath where practical - it typically uses only half as much water and energy.
• Shorter showers can save you money. In a household of three, each minute you add to your shower time is about $80 a year.^[3]

And remember, if your water use is metered, then every litre you save is saving you more money.

Notes:
^[1] Compared to an efficient shower head flow rate of 9l/min. Assuming three showers per day, shower duration of 9min, electric water heating at 23.7 cents per kWh. Calculated using the HERS hot water rating tool, documented in BRANZ report EC1475C "ANZHERS - Upgraded hot water rating algorithms", March 2009.
^[2] Based on Consumer NZ report "Appliance running costs", updated 2 July 2009.
^[3] Assuming three showers per day, shower flow rate of 9 l/min, electric water heating at 23.7 cents per kWh. Calculated using the HERS hot water rating tool, documented in BRANZ report EC1475C "ANZHERS - Upgraded hot water rating algorithms", March 2009.