Running is a thirsty business! To replenish water lost during exercise, runners should aim to drink between 200 and 400ml of water every 30 minutes, depending on the temperature, exertion levels, and many other factors. Staying hydrated is important to keep your body functioning well and legs moving quickly. To carry enough water for a day on the trails you have two options, a bottle or a reservoir. Bottles are a convenient way to carry water for a short period of time. For longer runs a hydration pack carried in a running backpack or hip pack will leave your arms free to balance and scramble. GO Outdoors stocks hydration reservoirs from Camelbak and Osprey.