There are several devices available to decrease the amount of water toilets, sinks and showers use.
Sink Flow Adjusters are available for sinks. They replace the aerator with one that slows the flow to a trickle with just a flip of the finger. These adjusters are an easy way to reduce the flow of water while brushing teeth, washing, shaving etc. They can be fancy or simple.
Shower Flow Reducers are easy to install too. It is a small valve you screw on between your showerhead and shower arm, with a button you push to reduce the flow while you lather up. You push the button back and your water returns full force- and the temperature remains as you originally set it.
Recirculation pumps are for those of you who are wasting a lot of water waiting for the hot water to arrive at the tap. These can be installed in a new home or as a retrofit. They circulate the hot water through the pipes for immediate delivery when you turn on the tap. Some retrofits fit under the sink and are easy enough to do for homeowner installation!
Ask at your local hardware or plumbing store for these handy gadgets!