1) The human body is composed of around 70% water, with the brain being 85% water and bones being 33% water. Water is essential for survival as humans can live without food for 4 weeks but only 3 days without water. 2) It is recommended that humans drink around 8 glasses of water per day to stay hydrated, as dehydration can cause kidney and brain problems. 3) Water is used for many daily activities at home like drinking, cooking, washing, bathing, showering, brushing teeth, and flushing toilets. On average, a family uses around 9-10 liters of water per day.