Platypus GravityWorks Water Filter System Edge CPCHigh capacity, pump free water filtration for groups and basecamps. Filtering up to 1. 75 liters a minute without any pumping, the high capacity GravityWorks Water Filter System filter is one of the easiest and fastest ways to get filtered water in the backcountry. With two different sizes6. 0L & 4. 0Lthe GravityWorks is ideal for bigger backpacking groups or basecamps. Offering an 8 or 12 liter total capacity, either model easily supplies filtered