Why I choose Soft Flasks to carry water on long runs

Over the last year or so I have tried out a variety of combinations of hydration bladder systems, hard water bottles and soft flasks, in the search for the ‘ideal’ combination of the best water bottles to use during long runs (using a race vest).

The combinations I have tried are as follows:

  • Hydration bladder only
  • Hydration bladder and hand-held bottle
  • Bottles (held on the front of a race vest – as supplied with the vest)
  • Soft flasks on the front of a race vest.

Initially, I thought the hydration bladder would win, hands down. Actually, I am not a big fan, as it has the following downsides

  1. you can’t see how much you have left – so you risk running out or getting really low on water when you don’t expect it
  2. it takes up most of the volume in my race vest, meaning I can’t carry much else in there (see picture above – the bladder takes up pretty much all of that main pocket when full)
  3. the liquid gets warm as it is sloshing around close to my back
  4. it is a faff to get it out to refill it – normally meaning the other bag contents need to be taken out (and possibly forgotten to put back) in order to do so.
  5. if you’re just using the hydration bladder and no other container, you can only have one drink, i.e. water, whereas having two bottles means you can have one full of water and use the other for electrolyte drinks, for example.
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So I prefer using two smaller bottles, carried on the front of the vest.


Hard bottles slosh, quite loudly, which can be annoying… It depends what mood I am in as to whether I’m fussed by this or not.

Keswick Mountain Festival 50k Ultra
Keswick Mountain Festival 50k Ultra

This is where soft flasks come in.

I did not appreciate the benefit of these until Alastair started using them and I got bottle-envy. The great advantages of these over normal hard plastic bottles are:

  1. they do not slosh (very much) as the soft sides collapse in when the volume of liquid is reduced
  2. they have a nice soft, easy flowing, rubber valve
  3. when they get emptier, they condense and take up less space.

When bought individually, they are not cheap – around $18-20, so if you are thinking of getting a race vest then spending c.£100 on the vest when it comes with two bottles (like the Salomon vests do) is not necessarily a bad deal.

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soft flasks running
Ultimate Direction ‘body bottles’. Soft hydration flasks, 420ml each

I bought Ultimate Direction’s 420ml bottles as I was expecting these to fit a bit better in the much smaller pockets in my UD vest as they are a bit smaller and shorter than the Salomon bottles. They just about fit, although when the bottles are relatively full, I find they flop about and have almost lost one due to it bouncing itself out of the pocket while running – so not ideal, and I use hair elastics to secure the tops to the vest when they are this full. When they get a bit emptier then they fit snugly in the pockets no problem. If I could choose again, I would go for the Salomon vest and bottles, because the bottles fit properly in the pockets, and also because the Salomon bottles are 500ml, and races often require you to carry water in a multiple of 500ml.

LARQ Bottle Review 2019 - The Self-Cleaning Water Bottle

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One final comment on these…

If you do choose to put any drinks other than water in a soft flask, don’t be surprised if the inside of the flask gets stained, probably yellow (for some reason not known to me). It has happened to the Salomon and UD flasks, despite cleaning out immediately after use and dishwashing them. It doesn’t affect the bottle other than there is a residual taste there which we cannot get rid of, so we use those stained bottles for electrolyte drinks and keep the other bottles for water.

Helen Dixon
Helen Dixonhttps://www.trailandkale.com
Trail Lover // Trail & Ultra Runner // Often found in the Mountains, Running, Hiking or Skiing // Seeking Peace, Beauty & Adventure.



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LARQ Bottle Review 2019 - The Self-Cleaning Water Bottle

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