OASSAY FlexFlow

Clean drinking water is easy to take for granted until a hike runs long, a stream looks questionable, or tap water arrives tasting of chlorine and old pipes. OASSAY FlexFlow is pitched at all of those situations, from improving everyday tap water to outdoor trips and emergency preparedness.

Two stages of filtration

According to the maker, FlexFlow meets NSF/ANSI standards and removes 99.999% of viruses, bacteria, parasites and microplastics. The first stage, NanoFlex Carbon, is designed to adsorb chlorine, odors and hardness components to improve taste. The second, a 0.1μm micro-membrane, physically blocks contaminants at or below 0.1 micrometers. OASSAY says results are verified both by third-party labs, including internationally accredited bodies such as SGS, and in its own facility, with at least 5% of each production lot randomly sampled.

One filter, three configurations

• Camp mode: a titanium or BPA-free PP cup nests around the bottle; the maker says the titanium cup can go directly over a flame to boil water.
• Run and city mode: part of the bottle is collapsible silicone, so it can shrink when empty and clip to a vest or belt.
• Filter-only mode: the 140g cartridge detaches and fits common 28mm-neck bottles, or can be held by hand to pass water through.

Flow rate and cartridge life

The maker quotes a flow rate of 20ml/s, with a light squeeze delivering filtered water without a wait. A backwash function, which flushes water in reverse, is said to clear over 90% of trapped debris and extend cartridge life to five times that of conventional products, allowing more than 300 days of continuous use per cartridge.

Other details include packaging made from recycled pulp that doubles as a storage box, a cap design inspired by the head of a woodpecker for sealing and ease of use, and two colors, Moss Green and Sand Gray. Optional accessories include the titanium and PP cups and a lightweight sling. According to the source, FlexFlow received a 2025 Golden Pin Design Award.