The Grayl Ultralight Purifier Bottle is an innovative water treatment solution designed to remove viruses, bacteria, protozoa, chemicals, and heavy metals from backcountry water sources. Unlike other water filters and treatment methods, the Grayl Purifier does not require batteries, ultraviolet light bulbs, hoses, straws, pumping, sucking, or waiting for a chemical reaction to complete. It also doesn’t require carrying an extra reservoir or container to drink from and doesn’t turn into a wet drippy thing that you need to store on the outside of your backpack to keep it from making your other gear wet while you continue on your journey. Intrigued?
The Grayl Purifier works like a French coffee press with an outer bottle and a plunger that fits inside it. You fill the outer bottle with water from a stream or lake and then press the plunger which has a filter at one end, into an outer bottle containing the water you want to purify. This forces the water in the outer bottle through the filter and into the plunger’s interior, which holds the purified water and doubles as a 16 oz. drinking cup that you can drink from directly. It also has a screw-on cap, so you have the option of carrying a pint of water with you if you don’t want to drink it all up on the spot. Another option is to pour the purified water out of the Grayl and into a larger bottle if you want to carry more at once.
Purifying 16 ounces of water takes 20 – 30 seconds and simply requires pushing the “plunger” into the bottle containing the dirty water. The best way to do this is to set the Grayl on the ground and push down on the plunger using your body weight. A surprising amount of force may be required; push down with your arms and let your body weight do the work. To pull the plunger (inner bottle) out of the outer bottle, pull on the handle of the cap. That’s the easiest way to get it out. If it sticks, due to suction, just persist. It’s not actually stuck and will come out.
The purifier cartridge in the Grayl uses a technology called electro-adsorption, where relatively large pores are overlaid with a positively-charged mesh that latches onto germs like little magnets. The larger pore size is easier to force water through, unlike other popular hollow-fiber filters (Sawyer Mini and Sawyer Point One), where you have to squeeze like mad to try to force water through the filter.
The Grayl is called a “water purifier” because it removes more substances than a “water filter”, including chemicals such as chlorine and iodine, and heavy metals including lead and arsenic. It also removes viruses, making it an excellent solution for international travel, as well.
- Removes 99.9999% of viruses (e.g. Rotavirus, Hepatitis A)
- Removes 99.9999% of bacteria (e.g. E coli, Salmonella)
- Removes 99.999% of protozoan cysts (e.g. Giardia, Cryptosporidium)
- Filters particulates (e.g. sediment, dirt), many chemicals (e.g. chlorine, benzene) and heavy metals (e.g. lead, arsenic)
Unlike other water filters or purifiers, the Grayl can be accidentally frozen and withstand up to three (3) freeze/thaw cycles. Beyond three cycles, purifier performance begins to diminish and the manufacturer recommends that the purifier cartridge be replaced. Still, that’s a handy feature in case you happen to get caught out in the cold unexpectedly.
The Grayl purification element is rated for 150 liters/300 uses, making it a better solution for occasional use on day hikes, mountain bike rides, and fishing trips, rather than extended backpacking trips and thru-hikes. The cost of an (Orange) Grayl replacement purifier cartridge is $24.95. Grayl sells a separate blue cartridge called the TAP filter ($14.95) for “frontcountry use”, which only removes taste and odor from water, but not biologicals. Don’t confuse them (the orange “backcountry” purifier cartridge is included when you purchase the bottle purifier.)
Grayl recommends that you replace the filter every 12 months because the activated carbon used to remove chemicals and heavy metals, can degrade over time. This can be limited by drying the filter between use and storing it in an air-tight bag. Since there’s no way to test when the activated carbon has degraded annual replacement is still advisable.
- Weight: 10.9 oz (309 g)
- Capacity: 16 oz (473 ml)
- Flow Rate: 15 seconds per 16 oz (2 liters/minute)
- The lifespan of Replaceable Purifier Cartridge: 300 uses (40 gal/150 L)
- Active Technology: Electroadsorption, ultra-powdered activated carbon, and silver treated zeolites
- Antimicrobial: Yes
- Chemical-free: Yes
- BPA free materials: Yes
Comparable Bottle-based Water Filters and Purifiers
|Make / Model||Type||Weight||Capacity||Replaceable Filter/Purifier||Price|
|Mizu V12 Vacuum Water Purifier Bottle||Purifier||15.4 oz||40 gallons||No||$74|
|RapidPure Intrepid Water Purifier Bottle||Purifier||9.2 oz||25 gallons||yes||$59|
|Lifestraw Flex Water Filter Bottle||Filter||1.7 oz||500 gallons||No||$35|
|Katadyn BeFree Water Filter Bottle||Filter||2.3 oz||250 gallons||Yes||$40|
|Lifestraw Go Water Filter Bottle||Filter||7.8 oz||264 gallons||Yes||$45|
Weighing 10.9 ounces (dry), the Grayl Ultralight Purifier Bottle is an innovative backcountry water treatment system that provides excellent protection against biological, chemical, and mineral contaminants, but is just as useful in more civilized or international settings to make your water safer to drink and taste better. I love the fact that it’s completely self-contained and includes an integrated cup and bottle which makes it super easy to pack and carry, without having to deal with extra hoses, reservoirs, bottles, batteries, straws, and wet floppy things on short hikes when there’s plenty of water around and you don’t need to carry much extra.
While you could use the Grayl for backpacking to purify more than 16 ounces of water at a time to carry, the purifier cartridge’s limited lifespan of 150 liters, the cost of replacement cartridges, and the time needed to process larger quantities of water make it a less desirable solution for long-distance backpacking or group trips. Still, I’m impressed by the ingenuity and ease of use of the Grayl Ultralight Purifier Bottle and think it’s an excellent water treatment solution, especially for hikers and outdoors people, who don’t normally have to filter or purify drinking water but want a low barrier alternative that is easy to bring along.
Disclosure: The author received a sample purifier bottle from Grayl but was under no obligation to publish a product review.Editor's note: Help support this site by making your next gear purchase through one of the links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored gear reviews, articles, and hiking guides.
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