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Grayl has created a water-treatment system that is two reservoirs and pump all in one compact unit.

Unless you’re willing to risk a most unpleasant bout of giardiasis or worse on your backcountry ventures, some kind of water-treatment system is a necessity. I much prefer filters to chemical treatments or boiling, so I was immediately intrigued by Grayl’s Geopress, which offers an interesting alternative to the hand-pump type filter I’ve been using.Unlike pump-operated filters, the Grayl Geopress combines a filter and water bottle in one unit. An inner bottle, with a replaceable filter attached, fits snugly inside an outer shell with a gasket providing a watertight seal between them. There are no moving parts likely to fail in the field, and very little opportunity for the kinds of accidental contamination that’s possible in pump-type filters, such as dropping an output hose into untreated water. Simply pull out the Geopress inner bottle and set it aside, then dip the outer shell in untreated water to fill it. Set it upright on a flat surface, reinsert the inner bottle, and open the pour spout’s threaded cap a half turn for venting air. Press the bottle down slowly and firmly into the outer shell. This forces the untreated water through the filter at the bottom of the inner bottle. It took me about 40 seconds to filter 24 ounces of water, much faster than pump-type filters I’ve used.

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