A few years ago I installed a low flow shower head with a built in slide shutoff valve. I'm going to have to start using the valve. The shower head by itself definitely lowered my water use.

During the last drought I visited a cousin in Calistoga. They had taken the pickup up into the hills to a spring that was still running and filled a few hundred one gallon jugs (not all on one trip). The garage floor was a sea of jugs. That was for toilet flushing and such.

There are toilets with a basin in the top. Do your business, wash your hands and when the water gets high enough in the tank the toilet automatically flushes.