For toddlers, offer a sippy cup or a bottle of water at least three times a day (not including juices and milk). Have it around the house during activity time, when the child watches TV, and specially when the child is outdoors in summertime. In the summer, much more water is needed, so always have a container of water handy in case your child wants to drink some while he/she plays.
For school-age children, you can pack a water bottle in their lunches. Let them know how important it is to keep hydrated, specially when they play outdoors in the summer, and when they go to physical education class. Any activity in which they are moving they need to stay as hydrated as possible.
The amount of cups of water per day for an average child should be 8 (1 cup size) glasses per day. Or basically 64 oz.