The LifeStraw Peak Series Solo is a compact, ultralight water filter designed for hikers, trail runners, bikepackers, and anyone who wants a tiny water filter in their kit. The Solo takes the proven LifeStraw membrane technology and wraps it in a pocket-friendly form factor that pairs with standard 28mm bottle threads.

• Weight (dry): 1.7 oz
• Removes: Bacteria –  99.999999% effective, Giardia and Cryptosporidium – 99.999% effective, microplastics – 99.999% effective
• Capacity: 2000 liters under ideal conditions, backflush often
• Pros: 28 mm thread compatible with most commercial water and soda bottles, caps at both ends, doesn’t leak, can be used as an inline filter, can be backflushed without special equipment
• Cons: As a water filter, it doesn’t remove viruses, dissolved chemicals, heavy metals, or salt. Additionally, if frozen, you’ll need to replace it.

What it is and how it works

The Peak Series Solo uses a 0.2-micron hollow fiber membrane to remove bacteria, parasites, and microplastics. LifeStraw rates the flow at up to 3L/min under ideal conditions, YMMV. The filter threads directly onto soft flasks and disposable water bottles with a 28mm opening, including Smartwater bottles and the CNOC Vesica soft bottle, which is now bundled with the Sawyer Squeeze. You can sip straight through the top valve or squeeze a bottle or soft flask to push clean water into a cook pot, reservoir, or another bottle. There’s a simple twist-to-open cap at the “dirty end” and a removable cover at the clean end to protect the mouthpiece from dirt and accidental cross-contamination.

The Lifestraw Peak Series Solo is roughly the size of a Nuun Electrolyte Sleeve

The Solo’s standout feature is its size and weight. It’s about the size of a Nuun Electrolyte Sleeve, and weighs 1.7  ounces dry, disappearing into a running vest or a hip belt pocket. Both the top and bottom caps seal well after use and don’t leak, which is a must-have that even the Sawyer Squeeze water filter (when purchased separately) can’t claim.

Filtration performance

On clear streams, the Solo delivers clean-tasting water with no plasticky aftertaste and good flow. Sipping directly works, but you’ll get a more consistent flow by gently squeezing a soft bottle. Water flow slows noticeably in water with more suspended solids, which is normal for hollow fiber filters. Backflushing helps. LifeStraw advocates a simple syringe-free method: reverse flushing by squeezing clean water through the outlet back toward the inlet, although the package the product comes in also includes a syringe. Pre-filtering your water with a clean bandana or coffee filter can also extend the performance of your water filter.

The Solo is compatible with water or soda bottles that have a 28 mm cap.

What it doesn’t protect against

While highly effective in removing bacteria, Giardia, Cryptosporidium, and microplastics, the Peak series Solo does not remove viruses, dissolved chemicals, heavy metals, or sale. It’s constructed using the same technology as other water filters designed for backcountry use in North America, where viruses are rare. In areas with potential viral contamination (crowded camps, disaster zones, or some international travel), pair it with Aquamira chlorine dioxide drops or chlorine dioxide tablets after filtering. If chemical contamination is a concern, you’ll need a different filter with activated carbon or a purifier that handles heavy metals. Or you can just buy bottled water if you’re near civilization.

Lifespan

LifeStraw rates the membrane for up to 2,000 liters under ideal conditions. Real-world lifespan depends on sediment load and maintenance, so regular backflushing is critical. Cold-weather caution: If the filter freezes after it’s been wet, internal fibers can crack and compromise safety. Keep it in an inner pocket near your body in freezing temps and replace it if you suspect a freeze event.

If you unscrew the top sip cap and remove its cap tether, you can even attach a hydration hose to the Solo and use it as an inline water filter. Very nifty.

Who it’s for

• Trail runners and backpackers who prioritize minimal weight and volume.
• Hikers who already carry 28mm soft flasks or disposable bottles.
• Emergency kits and glovebox preparedness are crucial, especially when space is tight.

Recommedation

The LifeStraw Peak Series Solo nails the ultralight, always-with-you requirement. It’s tiny, threads onto bottles you already carry, and delivers reliable pathogen protection for typical backcountry water. If you accept its limitations, then it’s one of the most convenient filters you can stash in a vest or pocket. For fast-and-light trips in places with relatively clean backcountry sources, it’s an easy recommendation.

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