Gravity Fed: Water Seeps Through Filter to be 'Cleaned'

Procuring clean water in the wilderness can be a pain. Pumps are hard work. Purifying tablets require a long wait. But last week, on a trek in northern California, I simply scooped some water from a stream and hung a bag in a tree.

The venue was the Lost Coast Trail, an ocean-hugging route where rivers pour out of green mountains and empty right into the sea. My water-filtering product of choice, the GravityWorks Filter from Platypus, gave our group near-instant access to drinkable water anywhere on the hike.

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As its name says, the GravityWorks Filter counts on nature’s primal pull (gravity) to coax water through a filter, no pumping required. The product, a system of tubes, water bags, and a filter cartridge in the middle, lets you grab untreated water then wait for gravity to do the work.

This system is not new, and we reviewed it in 2010 when Platypus called it the CleanStream Gravity Filter. A new name (GravityWorks Filter) and tweaks like a smaller filter and an overall reduced weight (from about 14 ounces to 10.5 ounces) are among the upgrades.

To operate the GravityWorks you fill the system’s “dirty” reservoir bag with lake or river water. Hang that bag in a tree or simply hold it up. Gravity does its thing, and water seeps out of a hose on the bottom, coursing through rubber tubing before entering a filter.

Clean water flows out the other end, slipping through a hose and collecting in the unit’s “clean” reservoir bag, ready to drink. The whole process takes just a couple minutes. There is very little effort required, allowing you to fill, hang the bag, and relax as water is dripping through from dirty to clean.

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GravityWorks Filter in action on California’s Lost Coast Trail

The GravityWorks’ filter unit has a pore size of .2 microns. That’s enough to eliminate bacteria, protozoa, and other “bugs” that may taint fresh water. It is not effective against viruses, but for most wild places that is not a worry.

Platypus quotes a filtering speed of 1.75 liters per minute, which was about what we saw on the Lost Coast. The unit costs $110, and it is made in the USA. Platypus cites 1,500 liters as the life of the filter, which can be replaced.

In a backpack, the GravityWorks folds and packs up fairly small. Stack the reservoir bags together, coil the hoses, and slip the filter unit in between — you’ll have a tidy water-cleaning system always at hand no matter where your trek may lead.

—Stephen Regenold is editor of GearJunkie.com. Connect with Regenold at Facebook.com/TheGearJunkie or on Twitter via @TheGearJunkie.

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Scene from Lost Coast Trail

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