Hydration Packs/ Camel baks
Go ahead a use a belt. My suggestion to you is to use your belt "between water stops" and get a drink at each water stop. That way you will be hydrated enough. I have not seen a "discrete" water belt. Many people use them, especially during 10Ks. They know that the water that they get at the water stops are not enough for them.
Without struggle, there is no progress.