Low-Flow Shower head
Remove your old shower head and replace it with a low-flow model. When you move, pack up the low-flow shower head and put the original shower head back on.
Displace Water in Your Toilet Tank
Find a plastic bottle. Fill it with gravel. Place it in your toilet tank. You can leave this for the next tenant or take it with you.
Hot Water Bottle/Electric Blanket
Instead of turning up the thermostat, you can invest in an electric blanket or a hot water bottle. Each of these uses less energy than a central heating system.
Repairs
One of the benefits of having a landlord is that they will fix things. Don’t let a slightly leaky faucet go unrepaired. Leaks account for 13% of home water usage. You can fix it yourself or get your landlord to do it.