I ran a race this week, Igot so dehydrated after a mile of jogging. How can I run without needing so much wate?

I ran 4 to 5 times a week...3 to 5 miles each time and sometimes even more. But when I ran in my neighborhood after work, I have lots of energy and usually have a drink of water every mile, no problem. But I ran a race this week (early in the morning) and I ate oatmeal, an egg sandwich, cup of coffee, 2 to 3 hours and a 3/4 bottle of water before the race. But when I was only a mile and a half away, I was so parched (they didn't give water halfway) I ran out of energy pretty quick...The usual easy 3 mile run for me became such a nightmare. By the time, I was halfway to the finish line, I was literally walking bec. I was so parched. Is there any runners out there that can help me? Someone told me about a gel that most runners eat to hydrate themselves while running. I guess I also ate too much before the race. But I'm a little underweight and I figured the extra food would be an extra energy boost. Did I do it all wrong?