Membrane Solutions Soft Flask with Filtration 400ml

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Light, compact, and fuss-free—ideal for quick fills on the move.

Membrane Solutions says: 

Take the hassle out of filtering water. The Soft Flask with Filtraiton 400ml allows you to store and filter water with ease! Combined with it’s compact size, impressive flow rate and filtration accuracy the Soft Flask with Filtraiton 400ml is a must have for any backpacking trip!

Our Verdict

I took the Membrane Solutions Soft Flask with Filtration (0.4L) out for a trip to the Lakes, and it performed admirably. At just 69g, it’s lightweight, and the soft-sided design means it packs down easily once empty. The flow rate was better than expected—no hand-cramping squeezes—and the water tasted clean every time.

The filter deals with bacteria, viruses, and microplastics, and while the 100-litre lifespan isn’t massive, it’s spot on for shorter multi-day trips or as a backup system. What I liked most was the simplicity—no backflushing or extra faff, just fill and drink. You’ll need to swap the filter occasionally, but for the weight, price and convenience, that’s a trade I’m happy with.

– Reviewed by Ultralight Outdoor Gear

Features

• Removes Bacteria, Parasites, Microplastics & Viruses
• Reduces Chemicals, Lead & Turbidity

Specifications

• Weighs: g
• Lifespan: 100 Litres
• Purification Method: Electroadsorption, and Ultra-Powdered Activated Carbon

Material & Construction

• Pore Size: 0.02µm(by positive charge adsorption)
• Fillter Technology: Electroadsorption, and Ultra-Powdered Activated Carbon

Help & advice:

• The Ultimate Guide to Water Treatment and Purification
• Time-Saver Guide to Water Purification