This article originally appeared on Backpacker
Unless you have a stomach of steel, you probably want to treat your backcountry water before you drink it. Luckily, there's no shortage of options for hydrating safely. While products like tablets, drops, and UV light work fine to treat water, filters are a popular choice because they're effective, long-lasting, and reliable. Even within the filter category, hikers can choose between hundreds of products that vary in style, price, and mechanism.
When choosing the right water filter for your needs, ask yourself the following questions:
Who do I backpack with? Do I need to filter water for a large group, a small group, or just myself?
How long is my outing? A multiweek backpacking trip demands different filtration than a long dayhike or overnight.
Is water abundant where I tend to hike, or will I go for miles between fill-ups?
Do I prefer to drink from a bottle, bladder, or straight from my filtration device?
What is the quality of the water sources where I most often backpack? Do I need to filter especially silty or mucky water, or do I hike mostly near clear streams? Am I concerned about viruses in addition to contaminants like bacteria?
Filters vs. Purifiers
First things first: Know whether you need a water filter or a water purifier. For most backpackers, a filter is suitable. What's the difference? Filters remove waterborne bacteria and protozoa, which is all that's necessary for most mountain lakes, streams, and ponds in North America. Purifiers offer an additional level of protection by also removing viruses from water, and occasionally heavy metals as well. While they're not necessary for most backcountry water sources on domestic backpacking trips, purifiers may be wise for international hiking trips where contaminated water is a concern. Purifiers tend to be more expensive and heavier than filters.
As the name suggests, these harness the power of gravity to treat water, allowing you to sit back and relax (or pitch your tent, cook dinner, or dig a cathole) while waiting for clean water. If you plan to filter most of your water in camp, a gravity filter like the MSR Guardian Gravity makes it easy. Simply fill a dirty water reservoir, hang it from a tree or place it on a slope, and let physics do the rest. These reservoirs often have capacity to filter a significant volume of water at once, making them great for large groups or families. For the same reason, they're often bulky and might be overkill for the solo backpacker.
Great for: Large groups, car camping, lazy hikers
Popular among thru-hikers, these are compact, easy to use, and ideal for filtering water multiple times throughout the day. Since squeeze filters like the Sawyer Squeeze typically filter no more than one or two liters per each refill, they're good for personal use. Plus, you can often drink straight from the filter, allowing you to cut a step from the process. Squeeze filters clean water instantly, which is great for hikers or runners who don't want to stop for long periods of time. They also tend to be compact, lightweight, and easy to disassemble and clean.
Great for: Solo hikers and small groups, ultralight backpackers, getting water fast
Pump filters like the Katadyn Vario are burly and reliable, making them good for repeated use either in groups or on long expeditions. Sure, it takes some muscle to pump your own water, but these devices tend to work fast, letting you treat large amounts of water more quickly than a squeeze filter. You can clean and service pumps in the field, making them ideal for long trips and dirty water sources. Long hoses also allow you to filter water without having to fill a bag or reservoir; for this reason, they're great for use on paddling trips or where water is harder to reach. Downside: They're heavier than squeeze and gravity filters.
Great for: Large groups and long trips
Some drinking bottles like the LifeStraw Go Stainless Steel have built-in filters in the form of straws or press-to-filter mechanisms. For hikers looking to fill and drink in a matter of seconds, these can offer a simple solution for personal hydration. Because you often need to drink straight from the bottle to filter, they're not good for sharing. They also don't allow you to treat water for non-drinking purposes like wound care, filling your pet's bowl, or cooking. Since the filter capacity is limited to the size of the bottle, these are ideal for hikes where water is abundant. Backpackers should consider their limitations before taking bottle filters on longer trips; but for dayhikers and solo travelers, they're a convenient and easy way to get clean water fast. (Downside: Some of the models we've used are tough to drink from--like sucking a thick milkshake through a straw.) Purification bottles are also great for international travel where water contamination is a concern both in the frontcountry and the backcountry.
Great for: Solo hikes in wet places, dayhikes, travel
These filters, such as the RapidPure Scout, often use the same mechanisms as gravity or squeeze filters, but can be integrated directly into a hose from a hydration bladder. Hikers who like to drink on-the-go instead of from a bottle will appreciate that the filter works as they drink. You don't have to stop to filter water; just fill a reservoir and go. These have similar limitations to bottle filters, however: because the sipping action drives the filtration, you can't clean water for first aid purposes or cooking.
Great for: Personal hydration, use with bladders and reservoirs
Made for drinking directly from the source, straw filters like the LifeStraw are compact and lightweight. They're good to have on hand for emergency use; throw one in your pack or first aid kit, and you might be grateful if you find yourself in a survival scenario. They're also ideal for trail runners and fast-and-light day missions where water is abundant. If you're moving with minimal equipment, a straw fits in a vest or a pocket and can be deployed for instant hydration. They require you to either drink straight out of a water source or somewhat awkwardly use the straw with a separate bottle, so they're not great for longer trips. Like bottles and inline filters, you have to suck to access the clean water, limiting its use.
Great for: Emergency backup hydration, trail running in wet environments
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