Letting yourself get dehydrated is the quickest way to compromise your performance and ruin your fun. A hydration system lets you carry a good amount (usually 2 or 3 litres) of water without interfering with your hands and with a convenient valve to drink from whenever you like. During intensive exercise, you'll need to drink around 1 litre of water every hour which means sipping little and often - much easier if you don't have to stop what you're doing and locate a bottle. Adding energy drink to the water makes the process even more effective. Make sure you choose a cleaning kit to go with your system or you'll be buying a new reservoir very soon! Different systems combine varying amounts of hydration capacity with a wide variety of cargo options. Everything from an energy bar to all the gear you need for a full day out.