Platypus Big Zip EVO Review (2026)

Where to buy

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Key specifications

What we like, and where it gives ground

What it is, and who it suits

The Big Zip EVO is a hydration reservoir, a soft water sack that sits in a pack or bike bag and feeds you through a long hose you sip from without stopping. Platypus built this model around one idea: make the mouth wide enough to solve the annoying parts of owning a bladder.

This review answers one question. Is the Big Zip EVO the right water system for how you walk and ride? We have not put this unit through our own long-term use, and we say so up front. Instead we read the maker's published specs against the jobs an Australian hiking or cycling hydration kit asks. Those jobs decide whether a bladder gets filled and carried.

If you sip steadily on the move and want an easy-to-care-for reservoir, this is the shortlist pick. If you prefer a hard bottle, that suits you better. The sections below take the reservoir apart piece by piece.

The wide zip mouth, and why it matters

Traditional bladders have a small round cap, and that narrow neck is the source of every bladder complaint. You cannot get ice in, you cannot reach a sponge in to scrub the inside, and drying is a guess. The Big Zip EVO unzips its whole top instead, opening a wide mouth that pours, ices and cleans with ease.

Fill it at a tap or a stream without a funnel. Drop in a scoop of ice to keep water cold on a hot day. Then run your hand, a brush or a cloth right inside to scrub away any film. This one design choice is the reason people who hate bladders often love this one.

When you are done, the zip lets you hang it open to dry fully, which is the single best defence against the mould that ruins neglected reservoirs. Convenience and hygiene, both solved by a wide mouth.

The liner and the taste of water

Bad bladders taste like a new shower curtain, and that taint makes you drink less, which is the opposite of the point. The Big Zip uses a taste-neutral, BPA-free inner that keeps water tasting like water, and a smooth liner that resists holding smells and films.

That matters most in Australia, where hot water sits in a dark pack all day. A poor liner turns lukewarm and foul. A good one, rinsed and dried between trips, keeps the draw pleasant enough that you sip often without thinking.

Care still counts. Rinse after use, dry it open, and give it a occasional deeper clean with a bladder tablet or bicarbonate solution. Treat the liner well and it stays taste-free for a long life.

Hose, valve and sipping on the move

Water leaves through a hose that routes over your shoulder, so you bite a valve and drink without breaking stride, stopping to find a bottle, or digging into a pack. On a long climb or a fast ride, that steady trickle is the whole reason a bladder beats bottles.

The hose ends in an on-the-go shutoff, so when you stop sipping it shuts off and stops the tube draining or leaking. Lay the hose, clip it to a strap, and top up without thinking. It is a small thing that changes how much you actually drink.

A hose does add failure points a bottle lacks. It can kink, catch on a branch or be punctured, and in cold alpine dawns the water in it can freeze. Manage those and the system is superb.

Capacity, packing and weight

The model we cover holds about three litres, which covers a long day or a hot stretch between refills. It fills into a flat, sloping shape designed to sit against the back panel of a compatible pack, keeping the weight high and close where it carries best.

Full, that is three kilograms of water, a real load. Carry only what the terrain and your refill plan demand, and size the bladder down on short walks. A half-used three-litre sack sloshes; a matched load carries cleanly.

Because you cannot see the level at a glance the way you can with a bottle, you learn to judge by weight or by how much you have drunk. It takes a trip to build the habit of knowing when to top up.

Cleaning and mould prevention

The wide zip makes the big job of a bladder, keeping it clean, genuinely easy, but it does not remove the chore. Left wet and closed, any reservoir grows mould, and the corners of a flat sack can hold damp where film starts.

The routine is simple. Rinse after each trip, scrub the inside with a brush through the open top, and hang it fully open to dry. Some owners freeze a clean dry bladder with a little water to curb mould between long spells of non-use.

Do not store it sealed with water inside for months, and never leave sugary drinks in it. A clean, dry, taste-free bladder is a happy one, and the wide zip is what makes keeping it that way realistic rather than a chore you skip.

How it compares to other water

It helps to set the Big Zip EVO against the two ways people carry water on a day out. Each wins in a different situation, and the choice rests on how and how much you drink.

Should you buy it?

Buy the Big Zip EVO if you hike or ride long enough to want hands-free sipping, and you will keep a bladder clean. The wide zip solves the filling, icing and drying pain that puts many people off hydration packs, and the liner keeps water tasting good.

Skip it if you prefer the simplicity and visible level of a hard bottle, or if you know you will not dry a reservoir between trips. A bottle, or a disciplined refill routine, fits those habits better.

Still deciding? See how it ranks in our hydration and water storage guide. To size your daily water before you choose a capacity, our water needs calculator does the maths.

Frequently asked questions

Is the Platypus Big Zip EVO easy to clean?

It is about as easy as a hydration bladder gets, which is its headline feature. The top unzips to a wide mouth, so you can pour a hand, a sponge or a brush right inside to scrub away any film, then hang it open to dry fully. A narrow cap-only bladder makes that near impossible, which is why so many go mouldy. The wide zip turns the main chore into a minute's work, but you still need to rinse and dry it after every trip.

Does water taste like plastic in the Big Zip?

The EVO uses a taste-neutral, BPA-free liner designed to keep water tasting like water rather than a new shower curtain. A smooth liner also resists holding smells and film. That matters on hot Australian days when water sits in a dark pack. Rinse it after use, dry it open and do an occasional deeper clean, and the draw stays pleasant enough that you sip often without thinking.

Can I put ice in the Big Zip EVO?

Yes, and the wide zip mouth is exactly why. A narrow-cap bladder will not accept cubes, but the Big Zip opens wide enough to drop in a scoop of ice before a hot walk or ride, keeping the water cool far longer. The flat shape also lays a slab of ice against the back panel. On a still, freezing alpine morning you would instead manage the hose so it does not freeze, so weigh cold water against a tube that can ice up.

What size Big Zip should I get for hiking?

Match the capacity to your day and your refill plan. The three-litre model covers a long day or a hot stretch between water sources, but full it is about three kilograms of weight, so carry only what the terrain demands. On short walks with easy refills, a smaller reservoir or a bottle wastes less pack space and sloshes less. Work out how much you truly drink, then size so you finish close to empty rather than lugging dead weight.

Is a bladder better than water bottles for hiking?

A bladder wins for steady hands-free sipping, because you bite a hose valve without stopping, digging into a pack or freeing a hand. That convenience usually means you drink more on long efforts. Bottles win for simplicity, a visible water level, easy refills and swap-ability, and where a hose might snag or freeze. For long hot days or fast riding many prefer the bladder; for short or technical outings, bottles are the easier tool.

How do I stop mould growing in my reservoir?

Dry it, which the wide zip makes possible. After each trip, rinse the inside, scrub any film through the open top, and hang the bladder fully open in the air until no damp remains. Mould starts in a closed, wet sack, so never store it sealed with water inside. Some owners freeze a clean, mostly dry bladder between uses, and an occasional bladder tablet or bicarbonate clean lifts any early film before it becomes a smell.