Yup.
I have 2 buckets in 2 corners of my shower - when full, these water my tomato plants.
When doing the dishes, I collect the water while im waiting for the hot stuff in a jug and that waters the roses.
I dont leave the tap running while I brush my teeth.
If you dont have one, install a toilet with a dual flush system - and always use the 1/2 flush (unless you need to use the big flush).
Also have a connector thingy and a long hose, so that when the washing machine drains it goes out onto the garden, instead of down the drain.
Quick showers.
Wash with a full load - be it clothes, dishes, etc - dont waste water on just 1/2 a load.