The human body is 65 percent water, which equates to 40 liters if we weigh 60 kg. Every day, we lose around 3 liters of water that must be replenished. However, the amount varies based on a number of parameters, including the animal's weight, size, and physical activity, as well as the outside temperature… You need to consume more water as you get older. The more activities we participate in, the more water our bodies expend and need to be replenished.