HydraPak
HydraPak 28mm Inline Filter Kit
- Protection: 8/10 What it removes from water, and how well that is proved.
- Flow rate: 4/10 How fast clean water comes through when it is new. Real flow drops as it clogs: see Ease of use.
- Weight: 10/10 How much it adds to your pack.
- Ease of use: 7/10 Filling, squeezing or pumping effort, how fast it clogs in peaty or silty water, and how easy it is to clean.
Adding a filter to a bottle or flask with a 28 mm neck, such as a 1 L Smartwater or HydraPak Stow
- Type
- Squeeze
- Removes viruses
- No
- Flow
- 1 L/min
- Weight
- 47 g
- Pore size
- 0.2 µm
- Rated life
- 1500 L
Where to buy
Ultralight Outdoor Gear £38.99 In stock. Free delivery. Shown with an RRP of £41.99. Free tracked UK delivery.
View at shop: Ultralight Outdoor GearHydraPak £42 Out of stock. HydraPak's UK shop, and the source of the list price. Delivery £3.60 by Royal Mail Tracked 48 (or £6.00 by DPD next day); free delivery starts at £50 or £75, so £3.60 applies to this price.
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
Protection
From maker's figures 8/10What it removes from water, and how well that is proved. 8: Clearly better than most.
0.2 µm single-stage hollow-fibre filter. HydraPak's fact sheet names the EPA Guide Standards and NSF P231 for bacteria and cysts: a named standard for bacteria and protozoa at 0.2 µm, which is the Protection 4 line. The shop page gives slightly different percentages and cites HSF 42, so we use the fact sheet. No virus claim, so not 5.
Flow rate
From maker's figures 4/10How fast clean water comes through when it is new. Real flow drops as it clogs: see Ease of use. 4: A bit below average.
HydraPak gives "more than 1 L/min", so we band 1 L/min, which is 0.6 to 1.19. No independent test timed this filter. Banded on HydraPak's figure.
Weight
From maker's figures 10/10How much it adds to your pack. 10: The best you can buy for this.
47 g for the filter (HydraPak fact sheet and shop page, "filter only"), under the 90 g line. The kit also holds a cap adapter and a backflush adapter. Ultralight Outdoor Gear lists 62 g, which is band 5 as well. Bikepacking.com gives 47 g.
Ease of use
Estimate from maker's specs: filter type 7/10Filling, squeezing or pumping effort, how fast it clogs in peaty or silty water, and how easy it is to clean. 7: Better than most.
Estimate from maker's specs
In short
Good for
- Adding a filter to a bottle or flask with a 28 mm neck, such as a 1 L Smartwater or HydraPak Stow
- Gravity or squeeze filtering from a HydraPak Seeker or Pioneer bag
- Drinking filtered water through the hose of a Plug-N-Play bladder
- Solo trips with a light, small filter
Strengths
- 47 g for the filter
- Three set-ups: squeeze from a Stow, gravity from a Seeker bag, or inline in a reservoir hose
- Threads onto 28 mm bottles and flasks, including a 1 L Smartwater bottle (Bikepacking.com)
- Backflush adapter and cap adapter come in the kit
- Rated to 1,500 L
Weaknesses
- Does not remove viruses
- HydraPak says only "more than 1 L/min", slower than a Sawyer Squeeze or Platypus QuickDraw on paper
- Needs some squeeze pressure to push water through (Bikepacking.com)
- Avoid freezing the filter, says HydraPak
- Only two independent reviews, and neither timed the flow
- No long-term wear report
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.