Best Backpacking Water Filters

KEY CONSIDERATIONS for the Best Backpacking Water Filters

Why do You Need to Filter Water?

So why filter or purify water in the first place? Even though the water in a flowing river may look crystal clear and clean, it could contain microscopic bacteria – such as E. Coli – or parasitic protozoa – such as Giardia. Both of these tiny interlopers can cause moderate to severe illnesses that will immediately ruin your backcountry trip. Therefore, we filter or purify water.

Filtering water removes bacteria and protozoa from water sources. Generally, this is all you need for any backcountry trips within developed areas (such as the U.S., Canada, and Europe). Meanwhile, purifying water also removes bacteria, protozoa, and viruses (such as norovirus) which are much smaller and more difficult to remove. While water purifiers aren’t necessarily required for most backcountry trips in the U.S., they can be invaluable on international trips to less developed areas of the world where water-borne viruses are a greater concern.

Filter/Purifier Type

Our first task is to take a look at the different types of filters and purifiers. Keep in mind that the exact type of water filter or purifying method you choose will depend on your group size, water source, and personal preference.

Inline/Gravity Filter

This filter type has been quickly gaining popularity in recent years. It typically features a dirty water reservoir filled from the water source that’s then hung or placed in a high position with a tube connected at the base. This tube then connects to the filter/purifier, which hangs beneath the dirty water reservoir, and a second tube runs from the filter down to a clean water reservoir at the bottom of the system. Gravity pulls water from the dirty water reservoir down through the filter/micropores that separate the impurities and then down to the clean water reservoir.

This type of filter can sometimes be fitted directly to a hydration reservoir/bladder and hose. In this case, the pressure of you pulling water through your hose mouthpiece forces water through the filter. This inline setup allows you to fill your hydration reservoir with dirty water but still get clean filtered water as you drink.

Gravity/Inline Filter Benefits:

• Hands-off filtering – let gravity do all the work.
• Can filter large volumes of water easily (great for multiple people)
• Easy to use for cooking, cleaning, or filling multiple water bottles
• Straightforward to clean and maintain

Inline Filter Drawbacks:

• Typically heavier and bulkier than other systems
• Can be tricky to set up in areas without trees where hanging the dirty water reservoir becomes a challenge.
• Hard to fill from shallow water sources – works best with deep or steadily flowing water sources.

Pump Filter

A pump filter uses pressure to pull water from the source via a tube and through the filter for purification. From the filter, another tube feeds the filtered water into a clean water reservoir (or directly into your water bottle). So, unlike gravity filters, pump filters need input from the user to work – normally in the form of a small hand pump.

Pump Filter Benefits:

• Better performance for shallow water sources
• Often a faster filtering process than gravity filters

Pump Filter Drawbacks:

• Takes time and effort to operate
• Harder to clean and maintain
• Often heavier than most other options

Straw Filter

As the name implies, a straw filter is essentially a beefy straw that filters the water as you suck water through it. With this device, you can drink from a water bottle (sometimes included with the straw filter) or drink directly from the source with your straw. Day-hikers and adventurers are typically the only folks using straw filters. This is because the straw only filters as you drink and doesn’t allow you to filter large quantities of water for cooking or carrying.

Straw Filter Benefits:

• Lightweight and portable
• Easy to use quickly – no setup
• Effective for on-the-go hydration

Straw Filter Drawbacks:

• Only filters water as you drink – doesn’t fill up water bottles or reservoirs with clean water

Bottle Filter

Bottle filters essentially incorporate a straw filter in a single integrated soft-sided bottle. All you need to do is squeeze the bottle to force water through the filter. You can drink directly from a bottle filter or squeeze/filter the water into a pot for cooking or Nalgene for storage. Some bottle filters can also function as gravity filters (although not as efficiently as a dedicated inline/gravity filter). However, you should check the instructions beforehand to ensure it has this functionality.

Bottle Filter Benefits:

• Easy to use
• Lightweight
• Can function as a gravity filter (select models only, check beforehand)

Bottle Filter Drawbacks:

• Difficult to filter large quantities of water
• Requires input from the user to function

Chemical Purifier

While filters physically remove impurities – bacteria and protozoa – chemical purifiers kill these organisms (along with viruses) to render them inert and harmless. Iodine and chlorine-based chemicals are the standards and typically render the water safe to drink after waiting the appropriate amount of time (be sure to read the instructions). Chemical purifiers will always come with specific instructions on how to use them, including the ratio of chemical-to-dirty water, wait time, and what bacteria, protozoa, and viruses they protect against.

Chemical Purifier Benefits:

• Very lightweight and compact
• No effort or pumping required
• Excellent secondary (emergency) purifying method to bring into the backcountry
• Can be used for large or small water containers

Chemical Purifier Drawbacks:

• Does not remove impurities from the water – silt, sand, grit, algae, etc. – and is best for reasonably clean water sources (such as glacial streams)
• Takes time to work, and you can’t drink water immediately after treatment
• Can sometimes leave a noticeable taste in the water
• Not effective against 100% of water contaminants – Cryptosporidium is a notable exception that is highly resistant to iodine and chlorine (chlorine dioxide is effective, however). Learn more about Cryptosporidium and filtering in this post from MSR.

UV Purifier

Like a chemical purifier, a UV purifier also inactivates bacteria, protozoa, and viruses. But in this case, the UV light scrambles the DNA of these organisms to prevent them from replicating and making you sick. A UV filter typically takes about 1-2 minutes to purify a liter of water and is either integrated into a bottle or is a small device that you insert into your water vessel and swirl around.

UV Purifier Benefits:

• Effective when used properly in clear water
• No pumping action required

UV Purifier Drawbacks:

• Will not function as well in silty or grimy water (which can shield harmful organisms from the UV light)
• Does not remove silt or grime from the water
• Requires batteries or occasional recharging

Filter Pore Size

As we’ve touched on earlier, most common filters remove bacteria and protozoa while purifiers also tackle viruses. The distinction between these two categories often lies in the filter pore size (the size of the holes that the water passes through). The smaller the pores, the more contaminants they snag and remove from the water.

According to the CDC, filter sizes of 1 micron or less will remove most protozoa, including Giardia and Cryptosporidium. Bacteria, however, are much smaller and require a filter size of 0.3 microns or less to be removed. Therefore, the best water filters will often hover in the 0.1-0.2 micron range in order to remove bacteria and protozoa.

Meanwhile, purifiers must also remove/neutralize viruses, but these little troublemakers are much smaller than bacteria. According to Encyclopedia Britannica, most viruses are between 20 and 250 nanometers (0.02 to 0.25 microns). Therefore, purifiers that still use mechanical filtration must have pore sizes of 0.02 microns or less. These ultra-small pore sizes are difficult and expensive to fabricate. For this reason, chemical and UV purification tend to be the most economical method to tackle viruses unless you’re willing to invest in a very high-quality filter.

Weight/Bulk

As with all our gear, weight and bulk play a prominent role in finding the best water filters for hiking. We all prefer that our equipment be exceptionally small and lightweight, but we have to weigh the pros and cons of that decision before investing. So let’s take a look.

The most lightweight water filters/purifiers are easily chemical purifiers. Each tablet or drop weighs just a fraction of an ounce and takes up almost no space in your pack. However, drawbacks ranging from taste to collecting already clear water (as chemicals don’t remove grit or algae) also limit chemical purifiers’ functionality. On the other end of the spectrum, heavy-duty pump filters can weigh from 1-2 lbs but offer excellent functionality for a variety of water sources.

So think about what you’re willing to carry, if you want a water filter or a purifier, and what you expect it to achieve. Answer these questions, and you’re well on your way to finding the best water filters for you.

Price

While a water filter won’t be the most expensive piece of gear you carry, it’s still worth considering the price. Chemical purifiers tend to be the most economical upfront at around $15 for a pack of 30 tablets. However, filters tend to provide better taste and can filter thousands of liters of water before they need to be replaced. In this regard, we see prices ranging from around $50 up to $275. This cost depends on the quality of the filter, extra features that come with it, and if you’re looking for protection against just bacteria and protozoa or if you want viruses to be removed as well.

So weigh your preferences and budget against your practical needs – i.e., the purifier vs. filter question. Once you settle on what you need, the type of filter or purifier that you prefer to carry, and your price range, you’ll be able to narrow down the field and find the best backpacking water filters for you.

MSR Thru-Link

Best Inline Water Filter

• MSRP: $49.95
• Type: Inline Filter – also functions as a gravity filter
• Effective Against: Bacteria and Protozoa
• Weight: 2.5 oz.

Pros: Lightweight – Very convenient for water reservoirs/bladders – Can double as a gravity filter at camp

Cons: Doesn’t come with compatible water vessels for gravity filter function – Only practical for one person (unless you’re sharing a water bladder)

Closer Look: For hikers who rely on a water reservoir/bladder for on-the-trail hydration, the Thru-Link from MSR is a convenient filter option to seamlessly plug into your hydration system. The lightweight 2.5 oz. filter is compatible with all hydration reservoirs on the market (according to MSR) and simply plugs into the hose system to filter water as you pull water through the system from the mouthpiece. At camp, the Thru-Link can be converted into a gravity filter system where gravity will pull water through the system when the water bladder (dirty water reservoir) is elevated above the filter. However, be aware that you’ll need an additional clean water vessel, bladder, or bottle to complete this gravity filter setup to collect the clean water after it passes through the filter.

Lastly, this inline filter is an awesome choice for solo hikers who use a hydration bladder on the trail. It’s lightweight, easy to pack, and seamlessly integrates into your hydration system. That said, it’s tricky to use as the primary filter for a larger group, so we tend to recommend it only for folks adventuring solo or for groups of two.

Find your MSR Thru-Link Water Filter

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MSR Guardian Gravity Purifier

Best Water Filter For International Travel

• MSRP: $299.95
• Type: Gravity Purifier
• Effective Against: Bacteria, Protozoa, and Viruses
• Weight: 1 lb. 2.7 oz.

Pros: Purifier removes viruses in addition to bacteria and protozoa – Purge hose for easy cleaning – Very durable

Cons: Expensive – Heavy

Closer Look: Most gravity filters’ greatest weakness is that they don’t remove any potential viruses from the water. While not a problem in the U.S. and Canada, it can be an obstacle in less developed parts of the world, where water-borne viruses are of greater concern. Enter the MSR Guardian purifier. It functions identically to most gravity filters, but the 0.02-micron pore size also removes viruses, making this one of the best backpacking water filters for international travel. Now, we do pay the price for this added protection with a higher up-front cost and a lower flow rate. At 1 liter in 2 minutes, the Guardian has almost half the flow rate of the Platypus GravityWorks. But these tradeoffs may well be worth it for folks looking for a reliable filter to use around the world.

We tested the MSR Guardian Gravity Filter while backpacking through the Himalayan Mountains, and it performed absolutely flawlessly. The Purge hose is a fantastic feature to help flush out the filter, and we utilized it with every use to give the system a quick flush and help keep the flow rate reasonable.

NOTE: MSR also makes the Guardian Pump Purifier that skyrockets the flow rate to 2.5 liters per minute. However, the price also increases dramatically for this pump purifier.

Find Your MSR Guardian Gravity Purifier

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