5 Most Common Water Treatment Methods for Backpackers

Water treatment is crucial for backpackers. After all, if you’ve put a lot of time and effort into planning a backpacking trip, you presumably will want to stay healthy during it so you can actually enjoy the hike.

Contaminants you’re likely to encounter while backpacking include bacteria such as E. coli and salmonella, protozoa such as cryptosporidium and giardia, and viruses such as rotavirus and norovirus.

There are additional considerations in areas with chemical contamination such as agricultural runoff. You may want to look into an activated carbon filter if this is a concern where you’ll be hiking,but for most long-trails, any of the methods discussed below are sufficient.

In choosing a water treatment method, backpackers must first identify where they’ll be hiking and what contaminants they’re likely to encounter there. That said, most methods

5 Water Treatment Methods for Backpackers

1. Hollow Fiber Filters

Hollow fiber filters are one of the most popular types of water filtration for thru-hikers and backpackers. In last year’s AT Thru-Hiker Survey, 93 percent of hikers used a mid-size filter such as the Sawyer Squeeze ($40.95) or the Katadyn BeFree ($44.95 for the 1L bladder version). They’re easy to use, lightweight, and relatively inexpensive for solo backpackers or small groups.

Hollow fiber filters work by running water through a tightly packed mesh of tubes with wider openings on the incoming water side than the outgoing water side. The openings on the outgoing water side are small enough to trap contaminants like bacteria and protozoa while allowing water molecules through. They do not filter out anything smaller than those outgoing holes, such as viruses.

Removes

• Bacteria
• Protozoa
• Sediment

Does NOT Remove

• Viruses
• Anything smaller than the stated filter size (usually 0.1 micron)

Hollow fiber filters need upkeep to maintain their performance. They must be backflushed or otherwise cleaned periodically to prevent the buildup of contaminants and maintain the flow rate.

Because these filters trap some water in the hollow fibers, they are susceptible to damage from freezing. Water expands when it freezes, potentially creating large cracks in the fibers that can allow contaminants through. On a trip where temperatures are likely to drop below freezing (32°F/0°C), keep the filter close to your body during the day and sleep with it in your sleeping bag or quilt at night.

Pros

• Lightweight
• Easy to use
• Inexpensive
• Water is ready for use instantly
• Filter out common contaminants along most long-distance hiking trails

Cons

• Freezing temperatures damage the filter
• Require regular maintenance to maintain flow fate
• Do not remove viruses

2. Pump Filters

Similar in function to hollow fiber filters, pump filters are a good option for backpacking with a group or a place where water sources might be shallow or sediment-heavy. Pump filters such as the MSR MiniWorks EX ($119.95) and the Katadyn Hiker Pro ($99.95) have a two-phase filter system. A pre-filter on the end of the uptake hose captures sediment, algae, and other large particulates, while another internal filter takes care of smaller contaminants like bacteria.

The internal filter is made either of hollow fibers or of ceramic. Most pumps can filter out anything smaller than 0.1 microns. These are effective at removing bacteria, protozoa, and sediment, but similarly to hollow fiber filters, they do not remove heavy metals, chemical contaminants, or (usually) viruses. Some, such as the MSR Guardian ($389.95), can remove viruses but the vast majority do not.

Removes

• Bacteria
• Protozoa
• Sediment

Does NOT Remove

• Viruses
• Anything smaller than the stated filter size (usually .2 microns)

Pump filters work by using a hand pump to suck water up from the source and push it through the filter. They have moving parts, increasing the complexity of the filter, and upping the odds of something breaking. The internal filter component is often replaceable. If the internal filter is ceramic or hollow fiber, it’s important to keep these filters from freezing.

Besides being more complex than their simple hollow-fiber counterparts, these filters are heavy: the lightest on the market is the Katadyn Hiker Pro at 11ounces, compared to the 2.3-ounce Katadyn BeFree. They’re also significantly more expensive than other treatment methods. Additionally, the pumps generally attach to wide-mouth water bottles like Nalgenes and require adapters for the thru-hiker staple of Smartwater bottles.

With this in mind, they’re not the best option for most thru-hikers and are best for groups backpacking together.

Pros

• Parts are replaceable
• Pre-filter sediment
• Water is ready for use instantly
• Filter out common contaminants along most long-distance hiking trails

Cons

• Heavy
• Expensive
• Freezing temperatures damage the filter

3. Chemical Treatment

For some hikers, in areas where viral contamination is likely, chemical treatment can serve as a primary or secondary treatment. Common treatments include Aquamira ($14.95), which utilizes chlorine dioxide, Potable Aqua ($9.95), which uses iodine, or even bleach administered from an eyedrop bottle.

In small concentrations, these chemicals are safe for human consumption and are effective at purifying water of bacteria, protozoa, and viruses. Chemical treatments do not remove physical particulates, including sediment. You may want or need secondary filtration, such as through a hollow fiber filter or even a bandana.

In places where hikers are likely to encounter exceptionally contaminated water, including where there is a higher potential for contamination from fecal matter from livestock or wildlife, chemical treatment is an excellent choice.

Removes

• Bacteria
• Protozoa
• Viruses

Does NOT Remove

• Sediment

Iodine in particular gives water an unpleasant taste. This can be worked around by using non-iodine chemical treatments or adding a flavoring packet after treatment.

It’s also important to note that chemical treatments require some wait time. You have to wait 5 minutes after mixing the two components of the Aquamira treatment before adding it to your water, for instance, and then another 20 to 30 minutes for the treatment to take effect. What’s more, you’ll have to wait an agonizing four hours for the drops to kill especially recalcitrant germs like Cryptosporidium.

Pros

• Effective at removing viruses
• Lightweight
• Inexpensive

Cons

• Does not remove physical particulate
• Can leave an aftertaste
• Requires waiting

4. UV Purifiers

A relative newcomer to the world of water purification, UV purifiers use UV light to kill organisms in water. The Steripen Ultra UV Water Purifier ($129.95) is one of the more popular options.

UV light can kill off bacteria, protozoa, and viruses in your water. Most UV purifiers work in about 90 seconds.

They can become ineffective in cloudy water. Pre-filtering is often necessary to achieve the clarity required for UV purification. This can be done with another commercial filter or with a bandana to remove large particulate matter.

Removes

• Bacteria
• Protozoa
• Viruses

Does NOT Remove

• Sediment

The Steripen, like many electronics, loses charge quickly in cold weather. You’ll need to carefully monitor the temperature and the charge level of both the Steripen and any external power banks.

Pros

• Effective at removing viruses
• Lightweight
• Easy to use, no wait time

Cons

• Requires charging and loses power quickly in cold weather
• Does not work well in sediment-heavy water
• Expensive

5. Boiling Water

The lowest-tech option on the list, boiling water is the oldest and one of the most effective methods of water treatment available, though it comes at the cost of time and high fuel use. The CDC recommends bringing water to a rolling boil for one full minute before it is safe to drink at sea level. That time increases to three minutes above 6,500 feet (1,990 meters). This can be fuel-intensive.

Removes

• Viruses
• Bacteria
• Protozoa

Does NOT Remove

• Sediment

The biggest challenge of boiling water is the time and fuel allotted for it. Most camp stoves take three and a half to five minutes to bring a liter of water to a rolling boil, and then the water must cool before it’s drinkable. This uses a lot of fuel, meaning you’ll need to carry more.

Generally, boiling water is a backup for other types of filtration should they fail. So while not the most practical on the list, it is important to know how to do it properly should the need arise.

Pros

• Removes viruses
• Can be done with supplies already in a backpacking kit

Cons

• Does not remove sediment
• High time cost
• High fuel usage

Conclusion

Water treatment options for backpackers are not one-size-fits-all, and it’s important to understand which options will suit your needs. A section hiker in Shenandoah National Park, where water spigots and infrastructure abound, and a thru-hiker in the New Mexico desert will have different needs. Understanding the various methods will allow you to pick the best option so you can enjoy your trip safely.

Featured image: Owen Eigenbrot photo. Graphic design by Chris Helm.