A drink you carry with you always reduces a riders comfort. We've tried saddlebags, but they hit the horses in canter. The best solution was a small backpack. It's ideal if you can fasten it at the belly and chest level. Whoever tried carrying a bottled drink, never tried it again, which says enough. When we go on longer rides that last 2-3 hours, we usually arrange for someone to bring us water, food, cameras, bathing suits, towels, oat and everything else.