Storm Valve™ is the name for the mouthpiece "drinking" valve of the Source hydration pack. Common valves need to be bitten to draw in water by suction, but for the Storm Valve™, the suction effect alone is sufficient to draw the liquid into the mouth. The flow rate of this type of valve is approximately 25% greater. The valve is secured with a cover that can be easily removed by a simple twist, which is reliable even in extreme cold.