We're pedantic in Australia about waste. Our environment is harsh, we experienced severe drought not so long ago so restrictions were set in place and the price of water and power skyrocketed.
Many guests from other countries have NO IDEA how to save resources. I have a doctor staying with me at the moment who leaves all the lights on. And spends a long time under the shower.
I simply told her we're very aware of the environment in Australia and could she please turn lights off, take shorter showers etc.
I have also put signs up near the taps = turn taps off while brushing teeth, turn tap off to soap your dishes, then rinse them.
That kind of thing.