VRG’s Research Manager produced lesson plans for children on water usage. Kids will learn about how much water is needed to produce various foods and other items, as well as how much water is used when flushing a toilet, taking a shower, brushing teeth, etc. These lesson plans are suitable for home schooling, as well as other educational settings.
See:
https://www.vrg.org/environment/K-2_lesson_plan_clean_water.php
https://www.vrg.org/environment/5-8_lesson_plan_water_conservation.php