HydraPak
HydraPak PocketFlask 500 ml Soft Flask
- Weight for its size: 9/10 How much it adds to your pack for the water it holds.
- Packed size (empty): 8/10 How much room it takes up when it is empty, for the water it holds.
Running vests, belts and small pockets where a 1 L flask does not fit
- Type
- Soft
- Capacity
- 0.5 L
- Weight
- 32 g
- Packed
- Not published
Where to buy
Rock+Run £14.50 In stock. Delivery cost not stated by the shop.
View at shop: Rock+RunUltralight Outdoor Gear £16.99 In stock. Free delivery. It lists 32 g and 500 ml.
View at shop: Ultralight Outdoor GearHydraPak £17 In stock. Delivery £3.60. HydraPak's UK shop. Free UK delivery over £50 on its shipping page (£75 on its shipping policy page); under that it is £3.60 by Royal Mail Tracked 48 or £6.00 by DPD next day.
View at shop: HydraPakPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Weight for its size
From maker's figures 9/10How much it adds to your pack for the water it holds. 9: Among the best you can buy for this.
HydraPak lists 32 g for 0.5 L (UK and US pages agree): 64 g per litre, under 100 g/L. Ultralight Outdoor Gear lists the same 32 g.
Packed size (empty)
Estimate from maker's specs: soft bottle: rolls up when empty 8/10How much room it takes up when it is empty, for the water it holds. 8: Clearly better than most.
Estimate from maker's specs
What reviewers say (out of 10)
Ratings marked * are from reviews and are not part of the trip score. They are reviewers' scores, not our own measurements. How we score
Leakproof*
Reviewers' average 8/10How reliably it stays sealed in a packed rucksack.
3 reviews on leakproof, e.g. "And then I can lock it again, stick it back in my pocket, and I know that it won't leak anywhere.".
In short
Good for
- Running vests, belts and small pockets where a 1 L flask does not fit
- A light spare for short routes
Strengths
- 32 g for 0.5 L, about 64 g per litre
- Low, tapered profile slips into narrow pockets
- 28 mm locking cap with a thumb switch; Trail Minded's video shows no drip when locked and upside down
- Shrinks as you drink so water does not slosh
- Can be frozen and filled with water up to 60 °C
- Beyond Lifetime Guarantee on defects
Weaknesses
- Holds only 500 ml
- Made for the snuggest running belts and leanest vest pockets, so check it fits your vest: HydraPak has a Flask Fit Finder
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (4)
- HydraPak: PocketFlask 500 ml (spec page)
- Trail Minded (YouTube): HydraPak PocketFlask 500mL locking cap review
- Pack Hacker: Finding The Best Collapsible Water Bottle for Travel (HydraPak PocketFlask 500 ml entry; team-tested roundup, updated 11 June 2026)
- HydraPak customer reviews: PocketFlask 500ml (26 listed at 4.2 out of 5, 21 flagged verified buyers; all read; maker's own Okendo feed, shared with the 2-pack)