Salomon Soft Flask XA Filter 490ml Review

Overview

Salomon was first to market with a bite valve squeeze filter, releasing the XA 490ml in 2021, and it remains the lightest weight option in the genre.

The concept is simple: fill the flask directly from a stream, tuck it back into your vest pocket, and sip filtered water through the bite valve without breaking stride.

Ideal for longer expeditions like ultra-trails, the Soft Flask XA Filter filters bacteria and protozoa from natural water sources, so you can drink easily and safely without needing to carry huge volumes of water.

It’s primarily aimed at trail runners and fastpackers, but any backpacker who front-mounts flasks will find it worth a look.

Key Specs

Spec	Value
Weight	52g (1.8 oz)
Capacity	490ml / 16oz
Cap Opening	42mm
Filter Lifespan	~1,000 liters
Filtration	Bacteria & protozoa
Material	TPU, BPA- & PVC-free
Filter Cartridge Weight	~36g (standalone)
Comparison	See how Soft Flask XA Filter compares to similar gear

Performance

Flow Rate & Drinking

The XA Filter’s headline performance feature is its flow rate. After two daylong trail runs, one user was very pleased — they got it to replace a Sawyer Mini for unsupported FKT attempts. It works better in a couple of ways when trying to go fast in cold weather: water flows through it quite a bit faster than the Sawyer, and it seems less susceptible to damage from freezing because the filter media is submerged in water rather than above it. That cold-weather point is worth flagging for anyone doing shoulder-season mountain travel. To operate the filter, simply fill the soft flask with water and drink directly from the mouthpiece. To filter water into another container, squeeze the mouthpiece and the flask at the same time. The filter has a high flow rate, which makes the whole process quick.

Filter Tech

Below the valve and inside the flask, Salomon’s XA filter safely and reliably filters out 99.99% of protozoa, Cryptosporidium, and bacteria.

The hollow-fiber membrane has obvious design similarities to the Katadyn BeFree.

The Salomon filter has a slightly longer body (112mm) but has a similar open frame design to the cage surrounding the filter membrane to improve cleaning and flow rate, though the XA filter does appear to have a greater amount of hollow-fibre filter membrane exposed.

Worth noting:

water filters remove 99.9999% of bacteria and 99.99% of protozoa, making water very safe to drink — but most filters, including this one, don’t effectively remove viruses. If you’re filtering water in an area with harmful viruses, a UV purifier is worth adding.

Cleaning

This is where the XA Filter starts to show its limits compared to newer competition. The only sanctioned cleaning method is a shake-and-swish — unlike the HydraPak UltraFlask, the XA only gets shake-and-swish style cleaning, with no backflush capability. A heavily silted source will shorten the filter’s useful life more quickly than the rated 1,000 liters suggests. If you’re pulling from glacial meltwater or silty rivers regularly, factor that in.

Flask Design

The soft-sided design collapses as you drink to minimize bounce and bulk.

The loop handle is helpful for dipping the flask in chilly water without getting your fingers too wet.

The flask body is made by HydraPak, which explains the familiar feel if you’ve used HydraPak products before.

Fit & Compatibility

Its long cylindrical shape is designed to fit Salomon vests and will slide into the front pocket of most hydration vests.

That “most” is doing some work, though.

The flask fits in a Nathan vest’s front pocket — until you add trail food as well, and then it’s too tall.

Being the tallest flask in its class is a genuine problem for some pockets.

Cross-brand compatibility has also tripped up some users. The 42mm threads are designed differently than the 500ml Speed Flask, which also has 42mm threads — and the filter doesn’t fit on those bottles. One user found that out mid-run when they planned to fill additional Speed Flasks and swap the filter between bottles, and Salomon avoids telling you which bottles it’s actually compatible with. The cap and filter combination should fit any HydraPak soft flask with a 42mm opening, and most other soft flasks with that size opening — but verify before you plan a refill strategy around it.

Durability

The HydraPak UltraFlask uses a thicker TPU plastic, which is more abrasion resistant than the thinner Salomon material.

The TPU body is not puncture-resistant — a sharp rock or an unlucky seam stress point can end a flask’s life early, and one reviewer noted a split developing on an older flask after sustained use.

That said, day-to-day durability seems fine for most users;

one user was on their second Salomon filter, with their first only starting to slow down after a year and a half of constant use.

Pros & Cons

Pros

• Lightest weight option in the category, fast flow rate, and narrowest form factor

• Bite valve means you never need to unscrew or flip anything mid-run
• Removable bail handle makes filling easy, especially in shallow or cold water

• Less susceptible to freeze damage than above-filter designs like the Sawyer Mini

• 100% BPA- and PVC-free TPU construction

Cons

• Rated for the shortest filter lifespan in its class (1,000L vs. 1,500L for HydraPak UltraFlask)

• No backflush capability — cleaning is shake-and-swish only

• Cap is very hard to remove on the soft-sided body; no protective cap over the mouthpiece, making it easy to contaminate the valve while filling

• Too tall for some vest pockets

• Cross-compatibility with other Salomon 42mm flasks is inconsistent and poorly documented

• Does not filter viruses — a gap shared with most hollow-fiber filters

Who Should Buy This

This flask is squarely aimed at trail runners and fastpackers who refill frequently from clean alpine or backcountry sources and want zero workflow disruption — fill, pocket, drink, repeat. If the shape of your running vest pockets accommodate long, skinny soft bottles best, look no further than the Salomon XA 490. It’s also a solid pick for anyone already invested in the Salomon vest ecosystem. If you’re a thru-hiker or backpacker who camps near silty water sources, values long filter life, or wants the option to backflush, the HydraPak UltraFlask is worth the extra scrutiny before you commit here.

Verdict

The Salomon Soft Flask XA Filter nails the core brief: it’s the lightest integrated bite-valve filter flask available, it flows fast, and it genuinely lets you hydrate without stopping. The trade-offs — no backflush, a shorter-than-average filter lifespan, and a bite valve with no protective cap — are real, but manageable for its target audience of runners and fastpackers who don’t need a filter to last five seasons. Although it has some limitations, the Salomon Soft Flask XA Filter 490ml is an excellent water filter for trail runners. Rating: 7.5/10.