If you have your own house it's worth considering putting a timer on your hot water cylinder.We have one on ours and it runs only between 9.00am and 4.00pm, so a cheaper part of the day, and when we don't use much hot water.We use an EATON TSQD1N0, and it cost around $200 installed.They are very easy to adjust the time on, so if you find you are running out, you can adjust to suit your needs.