-reuse it, like water that's used to wash something could be dumped to water the plants
-set stricter laws and regulations to stop corporation's industrial waste from contaminating lakes and ocean
-use greener design. like if you wash your hands that water could be directly used to flush the toilet.
-put up some environmental posters by the sink or drinking fountain or something to warn people to not waste water.
-set up campaigns and have a protest
-use better water pipes to prevent water leak or underground contamination.