The Platypus GravityWorks 4L is the group and base-camp filter. CleverHiker and OutdoorGearLab both score it 75 and call hands-free gravity filtration tough to beat for pairs and groups: hang the dirty bag, walk away, come back to clean water. It moves large volumes quickly and lasts longer than the personal squeeze filters. Heavy, bulky, and pricey, it is the wrong tool solo and unbeatable when you are filtering for several people.
- — Hands-free gravity filtration: hang the dirty bag and walk away while it fills the clean one
- — Filters large volumes fast, ideal for groups, couples, and base camps
- — Comes with both dirty and clean reservoirs plus the hose and hollow-fiber filter
- — Heaviest system here at 11.5 oz, overkill for solo ultralight trips
- — Bulky 4-liter bags take up more pack space than a personal filter