Platypus Big Zip EVO

The Platypus Big Zip EVO is a nicely designed bladder that has some unique features, including a quick disconnect on the drinking tube so the bladder can be removed from your hydration sleeve without the hassle of removing your drinking tube. The Platypus Big Zip EVO also features a large diameter drinking tube and HyFLO self-sealing bite valve that together provide a high flow leak free experience.

When paired with an MSR Thru-Link filter the Platypus Big Zip EVO allows for a fast scoop-and-go approach to filtering your water and the anti-microbial properties of the bladder material help keep the water clean. The Platypus Big Zip EVO also is available in four different sizes, so overall this is a nice solid choice as a water bladder for your backcountry adventures.

Overview

The Platypus Big Zip EVO is a hydration bladder recently introduced by Platypus that has a number of key features that includes taste-free materials, higher flow rates, a quick disconnect and a unique SlideLock closure system.  

The majority of the time that I have been evaluating the Platypus Big Zip EVO, I been using the bladder with the MSR Thru-Link water filter which I also reviewed. This review will primarily focus on the 2.0L version of the Platypus Big Zip EVO, but a 3.0L version was also made available to me and when I provide specific details with respect to size and capacities, I will also include information on both models. From a functional perspective the 2.0L and 3.0L models are identical, so any comments I make on the 2.0L model are directly applicable to the 3.0L model. 

The Platypus Big Zip EVO is available in four different configurations that include a 1.5L, 2.0L, 3.0L, and a unique 2.0L Lumbar version, so the Platypus Big Zip EVO should have a model that fits most people's needs for a hydration bladder.

My Impressions to Date

I have now had the Platypus Big Zip EVO for well over four months and have been bringing it on all of my regular hikes and snowshoe trips this winter and have found the Platypus to be a very nice hydration bladder with some nice features and very few faults.

I have been hiking and backpacking since the '70s and in that time I have utilized everything from Nalgene bottles, hydration bladders from a variety of manufactures, and now Smartwater bottles, so I have had experience with much of what has been available over the years.

After using the Platypus Big Zip EVO on some initial trips, one of the features I have come to really appreciate is the quick disconnect. While I have been using other brands of hydration bladders regularly (Osprey and CamelBak) before receiving the Platypus Big Zip EVO, they all have been older models that didn’t have the quick disconnect like is available on the Platypus Big Zip EVO.

Now that I have been using the Platypus Big Zip EVO with a quick disconnect, I don’t think I could go back to a hydration bladder without one. The quick disconnect really makes it easy to remove the Platypus Big Zip EVO from the hydration sleeve of your pack and eliminates the hassle of pulling out and then rerouting your drinking tube each and every time you fill the bladder, which I think is a great feature.  

The quick disconnect is also compatible with the MSR Thru-Link filter which when used together, enable a “scoop and go” approach to filter your water. I also did a review of the MSR Thru-Link Filter which is available here.

The opening used to fill the Platypus Big Zip EVO is located at the top of the bladder and consists of a zip-lock type seal that is secured by a handle that slides over the joint to keep it secure which Platypus refers to as the Secure SlideLock.

Here is a closeup of the closure/seal used on the Platypus Big Zip EVO showing the multiple ridges that interlock when the top of the bladder is closed.

In use I found the closure system to be easy to use, but did notice at colder temperatures in the high twenties (Fahrenheit) that the material is a little stiffer, but it never was an issue in closing/sealing the Platypus Big Zip EVO.

Here is a picture showing the details of the channel within the handle and how it straddles and captures the upper opening of the Platypus Big Zip EVO. The two flexible tabs at the close end of the handle snap over the end of the opening when the handle is fully installed and prevent the handle from sliding back off the opening.

One of the key features of the Platypus Big Zip EVO is the incorporation of a Handy Pincher Grip feature that is a gray plastic component permanently attached to the main bladder, that when pinched, holds the end of the bladder open so that it is easy to fill. 

The Pincher Grip is intended to be used with just one hand and in practice I found the method worked well. I always felt that I was able to securely hold the Platypus Big Zip EVO with just one hand and without any issue.

There were a few times when the reach to get down to the water was far enough that I didn’t feel like I could pinch the opening and still get down to the water, so I resorted to a less secure way (that means not recommended) to where I was able to pinch with my thumb and finger to keep the opening open, so the bladder would fill with water. 

You’ll notice in the picture above that when you are filling the Platypus Big Zip EVO that the handle is dangling in the water. The handle is secured to the Platypus Big Zip EVO by a small diameter elastic cord that seems secure enough when new, but with time it will most likely degrade to where you could potentially lose the handle. In the long run I may separate the handle so I don’t risk losing it while filling the bladder, but then again I have misplaced things at times, so it is nice that it is secured to the bladder. It's a little of a Catch 22 for me.

Later on in the review I will share some testing I did to see what would happen if you actually did lose the handle and had to continue your trip without it.

The handle of the Platypus Big Zip EVO in addition to being part of the closure system for the bladder is actually also a carrying handle. As a carrying handle it actually is pretty handy; the gap is a touch narrow for a gloved hand, but will easily accept the fingers of most people. 

The Platypus Big Zip EVO uses a nice large 5/16 diameter drinking tube which when combined with the HyFLO Self-Sealing Bite Valve really makes it a pleasure to use as the overall system allows very high flow in use and I would say supports Platypus’s claim of 50 percent faster flow. 

I have found that I can operate the shut-off valve with one hand and when closed I haven’t experienced any leakage, so from my experience to date, it seems like a very well designed shut-off valve. It is also worth mentioning that even with the main valve open the bite valve itself never leaked.

While I haven’t chosen to use it, The Platypus Big Zip EVO does come with a simple clip that can attach to one of your pack straps to help secure the drinking tube. Here is a picture of the clip and a closeup of the HyFLO Self Sealing Bite Valve and shut-off valve.

The Platypus Big Zip EVO is manufactured from materials that are certified taste-free, BPA-free, BPS-free, and phthalate-free, and while I did rinse the entire bladder and hose assembly before the first time I used it, I have never sensed or tasted anything unusual during the four plus months I have been using the Platypus Big Zip EVO.

I’ll be the first to admit that I’m not that disciplined when it comes to cleaning my hydration bladders, and for the most part unless something starts growing I probably won’t clean it. The Platypus Big Zip EVO may be the perfect bladder for me because the Polyurethane/Polyethylene film material the main bladder is made from is also embedded with silver-ions to help protect the clean water in your bladder from mold and bacteria.

Part of the reason that I haven't cleaned the Platypus Big Zip EVO yet is that I only have filled it with water and even when I used it with the MSR Thru-Link filter and unfiltered water from a steam, I've never felt the need to clean it afterwards due to how clean the water is here in the Washington Cascades (though some may disagree...).  

With respect to cleaning and disinfecting the Platypus Big Zip EVO, Platypus does provide some nice procedures to clean and disinfect the bladder using normal house-hold chemicals in the Frequently Asked Question and Document area on their website. The Platypus Big Zip EVO has a center baffle as mentioned earlier, but this would not impact being able to clean all the nooks and crannies of the bladder due to the nice straight access that the main zip-lock like opening provides.

Here is a picture of the center divider of the Platypus Big Zip EVO:

Testing The Zip-Lock Style Opening without the SlideLock Handle

Earlier in this review when I was discussing the SlideLock handle of the Platypus Big Zip EVO and I raised the question if the bladder of the Platypus Big Zip EVO would still be usable if you lost the SlideLock handle. To answer that question I decided to do some simple testing to see what type of external pressure the bladder could withstand without the zip-lock type closure opening up. To be clear, Platypus does not make any claim about what you should expect if you lost the SlideLock handle, but I thought it was a realistic scenario that could occur, and a significant one if you were on a multi-day trip and ended up with an unusable hydration bladder.

With the testing I wanted to simulate the pressure that the Platypus Big Zip EVO could potentially see if it was packed away in a pack and no longer had the SlideLock handle to secure the zip-lock style closure.

My first approach was to take a number of lead and steel items I had in my shop and simply stack them on the Platypus Big Zip EVO like shown in the picture below. 

With just over 55 pounds of weight on the 3.0L version of the Platypus Big Zip EVO, the closure for the bladder held tight with no leakage, which I thought was impressive and probably comparable to the pressure that might be exerted on the bladder if it was packed away in a pack.

While the first test I did was interesting, I really wanted to know what pressure or force acting on the side of the Platypus Big Zip EVO would cause the closure to open up. So for my next test I simple set the 3.0L version on my deck and slowly started to stand on the bladder using one foot to see if it would support my 195 pounds, which I found it couldn’t as the closure burst open and let the water out.

So for the next phase of my testing I introduced a bathroom scale where I would record a video of the display on the scale so I could record the approximate force I was applying with my body weight when the Platypus Big Zip EVO closure would burst open.  The picture below shows how I conducted the test and I found that the closure of the 3.0L version of the Platypus Big Zip EVO without the SlideLock handle would burst open at about 80 pounds, which is pretty substantial.

I did reinstall the SlideLock handle on the 3.0L version of the Platypus Big Zip EVO and found that the bladder/closure would take my fully body weight without any issue.

I repeated the same test using the 2.0L version of the Platypus Big Zip EVO and found that the bladder/closure without the SlideLock handle installed would support my full body weight without opening or leaking, which was very impressive.

So the short story here is that if you somehow did lose the SlideLock handle on your Platypus Big Zip EVO during an extended trip you should be able to continue to use the bladder for the remainder of your trip by spending a little time packing your pack in a way to minimize the pressure on the bladder.

After thinking about this for much too long, I did come up with a simple enhancement where I add a short section of some lightweight nylon cord I carry in my pack to the pinch feature on the Platypus Big Zip EVO. By using the cord to create a wrist loop this adds a secondary way to secure the handle and also provides a way to recover the Platypus Big Zip EVO if you accidentally let go while filling it in a stream with high current. 

Here is a picture of what it would look like.

Using the Platypus Big Zip EVO as a Dirty Bag in a Gravity Feed Filtration System

While I haven't used the Platypus Big Zip EVO as a Dirty Bag in a gravity filtration system, one of the other Review Corps Testers, LoneStranger, asked if I thought there would be any issues using it for this type of application. To answer that question I set up a basic gravity feed filtration system in my backyard using the 3.0L Platypus Big Zip EVO and an MSR Thru-Link filter as shown in the picture below.

Prior to setting up the system I had two concerns.  The first was if the drinking tube would kink as it is nice flexible tubing, and secondly, how would the fitting where the tubing attaches at the bottom of the bladder be loaded since it normally points up.  

The end result was that I didn't have any issues with kinking of the tubing as the lower fitting rotated outward and ended up pointing horizontal from its normal vertical orientation. Also, the fitting at the lower end of the bladder didn't look like it was being strained under the weight of the MSR Thru-Link filter, so all in all it looked like it would be fine for this type of application.

Here is a closeup of the lower fitting.

If I were to use this method in actual practice I might girth hitch a small sling to the drinking tube just beyond where it attaches to the lower fitting and then attach the other end to the pinch grip on the bladder to help take the load off of the lower fitting. Platypus does not make any claims that the Big Zip EVO can be used as a dirty bag in a gravity filtration system, but I don't see any reason why it couldn't in a pinch. If you specifically are looking for a gravity filtration system then the Platypus GravityWorks would be a great option, and it is available in 2L, 4L, and 6L sizes.

Physical Characteristics of the Platypus Big Zip EVO 

I’ve provided some basic information below on what I found the weight and physical dimensions to be and compared them to the values provide on the Platypus website. Overall, I found the Platypus website to accurately describe the 2.0L and 3.0L size of the Platypus Big Zip EVO.   

Weight of each of the Platypus Big Zip EVO models from the Platypus website:

• 1.5L - 5.6 oz
• 2.0L - 6.0 oz
• 2.0L Lumbar -5.4 oz
• 3.0L - 6.5 oz

My actual measured weights were right in line with the Platypus published weights for the 2.0L and 3.0L models I had to test.

• 2.0L - 6.0 oz
• 3.0L - 6.2 oz

To measure the capacity of the Platypus Big Zip EVO I filled the bladder up to the top and then seal the bladder using the SlideLock closure system so the bladder was full with no air pockets and then I would measure the quantity of water that remained in the bladder. For the 2.0L and 3.0L bladders I had to evaluate, I found the liquid capacity to be as follows:

• 2.0L Version - 2.25L Actual measured
• 3.0L Version - 2.9L Actual Measured 

For physical dimensions that would be useful for determining if the Platypus Big Zip EVO would fit in a hydration sleeve of a pack, I filled the bladder with water and then set it on a flat surface like as shown above and then recorded the dimensions shown below. 

• 2.0L - 14.0 in long x 6.5 in wide x 2.625 inches thick
• 3.0L - 16.5 in long x 6.75 in wide x 2.75 inches thick

Hose Lengths

• 2.0L -  short hose 10.25 inches long, long hose 33.25 inches long
• 3.0L -  short hose 11.75 inches long, long hose 31.0 inches long 

The physical dimensions I shared above of the Big Zip EVO are influenced by an integral baffle in the center of the bladder that prevents the bladder from becoming a round sausage when it is filled with water. How the Platypus Big Zip EVO might fit in the hydration sleeve of your pack is dependent on which pack you use, but for the hydration sleeve of my medium size ULA Circuit pack I found it fit either the 2.0L or 3.0L version of the Platypus Big Zip EVO.

Here is a picture of the larger 3.0L Platypus Big Zip EVO slid into my ULA Circuit hydration sleeve.

Price

The listed the price for the available versions of the Platypus Big Zip EVO below and they are in line with the cost of other hydration bladders with similar features from other well-known manufactures.  

• 1.5L - $36.95
• 2.0L - $37.95
• 2.0L Lumbar - $36.95
• 3.0L - $39.95

Summary and Recommendation

I found the Platypus Big Zip EVO to overall be a very nice hydration bladder and I wouldn’t hesitate to recommend it to anyone looking to purchase their next hydration bladder. The combination of very high flow, an easy to fill design, a useful quick disconnect, and Platypus quality make this a solid choice for anyone looking to upgrade or purchase their first hydration bladder.  

Many thanks to both Trailspace and Platypus for the opportunity to evaluate and test the Platypus Big Zip EVO for the Trailspace Gear Review Corps!

Background

I have been using the Platypus Big Zip EVO for over four months now on all of my regular hikes and snowshoe trips. In addition, I have been hiking and climbing since the '70s and at one point or another have used a variety of hydration bladders, Nalgene bottles, Smartwater bottles, etc.