HydraPak
HydraPak UltraFlask Speed 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.
Lowest price we found
£18.99 at Ultralight Outdoor Gear
Go to Ultralight Outdoor Gear Compare 3 shopsFast hiking and long days where water should sit in a pack or larger vest pocket
- Type
- Soft
- Capacity
- 0.5 L
- Weight
- 42 g
- Packed
- Not published
Where to buy
Ultralight Outdoor Gear £18.99 In stock. Free delivery. Shop shows RRP £19.99. Its page lists the same 42 g and 500 mL.
View at shop: Ultralight Outdoor GearSportsshoes £19.99 In stock. Delivery £4.99. Standard+ 48 UK delivery £4.99 on its page. Its site-wide 15% code is not included in the price.
View at shop: SportsshoesHydraPak £20 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 UK lists 42 g for 0.5 L: 84 g per litre, under 100 g/L.
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
In short
Good for
- Fast hiking and long days where water should sit in a pack or larger vest pocket
- A light 500 mL soft flask that doubles as a clean-water bottle for a 42 mm filter cap
- Drink mix and ice: the 42 mm opening is wide
Strengths
- 42 g for 500 mL: 84 g per litre, very light for its size
- Wider form and a 3D-welded base for a snug fit in pack and larger vest pockets (HydraPak)
- SpeedFill flip-top cap for one-hand refills; bite valve that seals after each sip
- TPU body with RF-welded seams; HydraPak lists a working range up to 60 °C and says it can be frozen
- 42 mm thread pairs with HydraPak's 42 mm filter cap
- High flow and easy to clean, says the one video reviewer
Weaknesses
- Only 500 mL: two are needed to match a 1 L bottle
- The same reviewer finds the cap tricky to open with tired hands, and the thread can cross
- Only 1 independent source found, so ease of use and durability are estimates, not reviewed scores
- HydraPak gives no rolled-up size, so we cannot score packed size
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.