Sunday, 7 May 2017

OMM Flexi Flask vs Platypus Soft Bottle

After many happy years of service I replaced my old and badly worn day pack, an OMM Adventure Light, with another of the same model last August. It’s a great pack and I’d happily recommend it. It has though, been updated several times since my old one. One of these updates it seems has been to make the mesh bottle pockets a good bit slimmer to the point where I struggle to get my old oval Sigg bottles to fit. Fine, it was probably time I got some lighter and more compact bottles anyway then I thought.

I had a quick look online and decided to play it safe. I went with the OMM Flexi Flask 500ml x2 as I was pretty much guaranteed that they would fit well in the pockets and the reduced weight and empty collapsibility also appealed.

When they arrived they certainly looked to tick all the boxes. They’re quite slim and constructed from a very soft plastic film that does indeed make them easy to get into the pockets with no snagging, however they are so soft that they cannot stand up on their own (not a huge issue). They also collapse down to a very compact size when empty. Weight is a very welcome low of 27grams and a good chunk of that is the bite valve style nozzle.

Sounds perfect then I hear you say? Well no. There are two issues I found, one with the potential for accidents if you don’t follow the warnings (and common sense) and the other that pretty much undermines the products usefulness and entire purpose to the point that I’d advise you to stay well away.

The first point is with the construction of the OMM Flexi Flask. It appears that the seams are thermally welded and aren’t really up to the job of holding hot liquids. I tested this myself with water from the kettle and almost immediately had a catastrophic failure of one of the short bottom seams. See pic below...To be fair to OMM though, I’m sure that I do recall seeing something on the packaging warning me not to do this (I cannot check their website to confirm as it appears to be down at the moment) and it’s also not really an expected use of the Flexi Flask or anything that I or anyone in their right mind would recommend anyway given that... A) You’d very likely burn yourself through the wall of the material. And B) It has a bite valve so would have the serious potential to leak inside a sleeping bag anyway if you were to attempt to use it inside a sock as a makeshift hot water bottle (something I’ve done on occasion in the past with Sigg type bottles). Either way, I’d be inclined to give OMM the benefit of the doubt here anyway as you’d have to be pretty daft to think it was a good idea. I only did it as I wanted to see if it would actually fail and had already decided that they weren’t fit for purpose which brings me to my next point.

The product bumf I can find on every webstore (again I cannot confirm on their website as it’s still down) selling these flexi flasks is that the material is “BPA, PVC, Phalate free and will not taint taste.” Great! I like to be in the knowledge that I’m not ingesting harmful chemicals potentially leaching out and although I have no way of measuring whether or not this claim is accurate, again I’ll give them the benefit of the doubt. The will not taint taste claim is however complete rubbish. Every time I used these flasks I could taste the plastic. I tried washing and rinsing them out many, many times but it was always the same. Water poured in and drunk straight out was fine but water left in there for anything longer that half an hour had an overwhelming plastic taste. I could even taste it through my Coffee or Milo. It tastes rank and frankly ruins what could have been a pretty good product. Even if there is technically nothing “harmful” leaching out of the material, something must be as confirmed by my own taste buds. My advice is to avoid these like the plague. I 100% would not recommend the OMM Flexi Flask to anyone and to be honest am pretty annoyed that I spent my own hard earned cash on these.

So it was back to the drawing board then in my search for a lightweight, compact (and collapsing if possible) bottle to fit in my OMM Adventure Light pockets. In my searches I’d already come across the Platypus Soft Bottle and had plumped for the OMM one for the positives mentioned above. Sometime in the distant past I’d already tried the Platypus Soft Bottle and not really gotten on well with it mainly due to it being the 1 litre size. This meant that it was too long for the bottle pockets and flopped around over the top of them constantly threatening to fall out when half full. I also seem to recall the welded seams catching a bit on the mesh bottle pockets but that may well also have been a function of the too big size plus the fact that my bottle pockets were already quite badly holed after many years of abuse. Other than that I had no complaints and have happily used a larger 3litre platypus for many years as a means of collecting and storing water for camp. I tentatively with crossed fingers decided to have a shot at a 500ml size Platypus Soft Bottle then.

Weight was pretty much the same and although a little bit wider than the OMM Flexi Flask they are flatter and flexible so still squash easily and conform to the bottle pocket’s diameter. The length of the 500mI version is also far better for bottle pocket carry with nothing flopping about. The material is a quite a bit stiffer though, so rather than crushing down it tends to work better if rolled up when empty. Collapsed size compared to the OMM is still pretty similar though. The Platypus Soft Bottle does stand up on its own due to the shape of the bottom which may or may not be important to you? Personally I discovered that I like it as it means I can put the Platypus down with the lid off when cooking etc. Platypus give the usual assurances regarding BPA, BPS and Poly-carbonate etc but more importantly though, I can confirm that there is no taste issue.

Any negatives then? Well the sharper eyed among you will notice that despite my link, that is not a push pull cap in my photos. Originally I tried the push pull cap thinking it would be easier to drink on the go but found the push/pull action to be quite stiff and uncomfortable on my teeth to open and quite hard to ensure a properly closed (and therefore sealed) position. Luckily I had some old Platypus screw tops at my disposal so swapped them out and to be honest find them just as quick and convenient to use. The bonus being that the Platypus Soft Bottle weight now goes down to 20grams. Result! As mentioned the material is still stiffer than that of the OMM one and the wider seams do still tend to catch on stuff but with the smaller size bottle, in real life use, I’ve not found them to be an issue and they do go in and out of my bottle pockets one handed when wearing the pack with no problems. I will be keeping an eye on the pocket mesh for wear and tear though and report back if necessary. Some side by side photos below for comparison.

Would I recommend the Platypus Soft Bottle then? Absolutely and the proof is that I already have gone and spent my money on another one, and you will see them in constant use if any of you are following this place. I would however caution you to pick your size carefully and would tend to recommend the normal cap over the push pull cap.


  1. Nice report. Shame about those OMM bottles imparting a taste to the water. That's definitely a deal killer for me. I'll be sticking with my Platypus and Evernew water bladders.

    Thanks for putting this together,


    1. Thanks Hikin' Jim. Just clicked on your Blogger profile there. I didn't realise that you had another Blog as well as the Adventures In Stoving. I thoroughly enjoy the stoves Blog and now look forward to having a good read at your trip reports.


Blog Archive