Handheld desalinators operating on the principle of reverse osmosis are available for emergency use in lifeboats. Sometimes they appear for sale unused in their original packaging at a very steep discount because they have been replaced at a scheduled interval by their owners (merchant marines, navies, etc). Is there any reliable means to assess the condition of the device and determine if it is reliable enough either for convenience (reducing the quantity of fresh water carried) or for possible life-sustaining use? Checking the condition of mechanical parts (pivots, levers, body) and of any seals (no cracks) seems straightforward, but what about the reverse osmosis membrane itself?
(Inspired by Portable desalination hand pump filter life?)