Everyone knows that drinking water — and making sure it's a substantial amount — is important for a healthy lifestyle. Water lubricates your joints, protects your spinal cord and other sensitive tissues, and helps to regulate your body temperature. This would make sense since 60 percent of the human adult body is made up of water. According to a 2013 Centers for Disease Control and Prevention study, 43 percent of adults drink less than four cups of water a day, 36 percent drink one to three cups, and seven percent drink none at all.