Since you are going in August, you will absolutely need to have water with you at all times. Stopping occasionally for a drink isn't going to keep you going in the August heat/humdity..you need to be drinking constantly, especially the kiddos. We saw more people getting physically sick from the heat.

We went in June and brought these:
They were an absolute lifesaver. They have a filter built into the top 1/2 of the bottle. You just twist them open and fill them up. When you drink, the water goes through the filter. We would fill them with ice in the morning before we left the resort, then refill with ice throughout the day at the CS places. You can fill them with water from any of the drinking fountains and the filter made it taste as clean and fresh as bottled water.

HTH.