The Platypus Big Zip LP, now updated to the Platypus Big Zip EVO, is the only zip top bladder in our review, and although it does not score as highly as the other bladders it can be considered a good all-rounder that performs well in most activities.
It lost marks on its components though. The bite valve was our least favourite, and the quick release hose system is only somewhat compatible to the others due as the hose attachment is orientated horizontally whilst the others are vertical.
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Platypus Biz Zip LP
The Platypus Big Zip EVO will work well in a general, not too demanding hiking, walking or biking environment. Though it has a thick plastic outer which makes it less prone to punctures, it is the only hydration bladder that we were able to pick apart at the seams.
Because the Big Zip LP does not have as many optional accessories as some of the other bladders do our overall impression of this bladder is one of simplicity. We do however like that it sports a hanger on the lid closure as this is pretty handy around camp if you would need to hang it or carry it somewhere.
As one of the more expensive hydration bladders that we have reviewed so far, we do feel a little perplexed about the price and would recommend the Hydrapak Shape-Shift Reservoir if you are looking for a lightweight and active hydration bladder, or the CamelBak Crux Reservoir as a better all-rounder.
See Other Hydration Packs
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Size and Profile
This is the only hydration bladder that we would recommend buying a smaller size in – either the 1.5L or the 2L and this is because the wider profile already places a limit on the number of backpacks and running packs that the Platypus Big Zip LP fits comfortably into.
Hydration Pack Opening Type
The zip top opening is similar to the fold top opening except that it has a zip top which is pressed shut like a zip lock bag, and then a closure attachment is inserted over the zip. We like the closure attachment with its very handy hanger which none of the other bladders have as this proved useful for hanging or carrying the bladder.
Sadly, the zip top is not quite as easy to refill as the fold top bladders are. The zip top opening is slightly smaller and the same sentiments that apply to refilling the fold top work for the zip top too. It is easily refilled from a flowing stream or a deep basin but has the same problem when refilling from a shallow basin. That is, if the bladder is not completely vertical, you lose the ability to fill it to capacity due to it folding over.
Bite Valve Size
The Platypus Big Zip LP features a larger bite valve which we found made it difficult to suck water out of. Its saving grace is the switch valve mechanism and the fact that it can be swapped out for other bite valves.
Ease of Cleaning
The opening of the Platypus Big Zip LP means that you can easily get a scrubbing brush into the reservoir compartment to clean out but because this one has a smaller bottle neck opening it is more difficult to get your hand in to turn the bladder inside out to clean like we did with the fold top hydration bladders.
Component Compatibility and Interchangeability
Our main qualm with the Platypus Big Zip LP is the hose connection which is horizontally orientated whilst all other bladders we reviewed were vertically orientated.
Without the addition of a 90 degree connector, the hose systems are not compatible with each other. Whilst adding the connector is not a huge task, it just seems a little unnecessary.
The hose connection orientation is also a little awkward without the connector as the hose tends to stick out at an inconvenient angle.
Luckily, the mouthpiece is fully interchangeable and we would recommend opting for the CamelBak Crux Reservoir medium size bite valve which is way more ergonomic than the large one of the Platypus Big Zip LP.