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Reviews > Hydration Systems > Bladders > Platypus Big Zip LP Reservoir 3 L > Owner Review by Marina Batzke

August 20, 2017


NAME: Marina Batzke
EMAIL: mbbp2013 (at) yahoo (dot) com
AGE: 57
LOCATION: Los Angeles County, California, USA
HEIGHT: 5' 5" (1.65 m)
WEIGHT: 132 lb (60.00 kg)

I converted from day hiking and car camping to backpacking in 2013. My backpacking trips are one or two weekend excursions per month in Southern California. The locations range from Joshua Tree National Park desert areas in the cooler months to mountainous elevations in the summer months. I always hike with a group and like the gear talk in camp. While I am looking for ways to lighten my pack, I am not an ultra-lighter: I like sleeping in a tent with a sleeping bag on a comfortable pad. In January 2017, I added snowshoeing to my winter activities.


Manufacturer: Cascade Designs, Inc.
Year purchased: February 2017
Made in the U.S.A. of U.S. and Imported Materials
Manufacturer's Website:
MSRP: US$34.95 for 1.5 L and 2 L. US$36.95 for 3 L.
Listed Weight: 6 oz (170 g) for 3 L
Measured Weight: 6.17 oz (175 g) Bladder, Slidelock + Hose

The Platypus Big Zip LP is described as a superior hydration system with a low profile bladder. It is available in 1.5 L (50 fl oz), 2 L (70 fl oz) and 3 L (100 fl oz) bladder sizes. I own the 3 L size. The Platypus Big Zip LP bladder itself is made from transparent polyurethane and described as BPA- (Bisphenol-A), BPS- (Bisphenol-S) and phthalate-free for taste-free water. At its top end, the bladder has a plastic zipper type closure: three hard plastic ridges on one side and three on the other get pressed together for a tight seal. A blue hard-plastic slider called Slidelock is attached to the top of the bladder with an elastic band. By inserting this blue slider over the bladder top end and moving the slider to the left, I press closed the zipper. An imprint near the top says: Slide shut to secure, invert to test. This has always worked extremely well. The bladder with the slider at its top has not once leaked. On its inside, in the center the bladder has a plastic separator. It makes sure that this big 3 L bladder is not turning into a round ball full of water, once filled. Instead it is a nicely low profile 2.5 in (6.4 cm) thick filled bladder with a high carrying capacity.
the blue Slidelock squeezes closed the zipper

dish towel inserted for improved drying

When I want to refill the bladder or clean it, I move the blue slider to the right. It is good that this slider is attached to the bladder with the black elastic band, so I cannot misplace it or drop it in the dirt. I then pull open the zipper and have 4.5 in (11.4 cm) of wide open bladder mouth to refill the bladder. This wide mouth opening is also perfect for cleaning. Once I return from a backpacking trip, I pour out all trip-filtered water. Then I add a tap water and baking soda solution, shake that inside the bladder and finally drain it out through the hose and mouthpiece. I then insert a cotton dish towel into the bladder with my hand and stuff the towel to the left and to the right side of the separator. I insert the blue slider upright into the wide mouth, so the zipper stays open. I let this assembly rest on a flat surface for a few days, so the inside dries completely. While writing this review, I noticed a few stains inside the hose. The manufacturer offers two solutions: a replacement Big Zip Drink Tube Kit or alternatively a Platypus Cleaning Kit.

The 40 in (102 cm) long hose is light blue and has the trade name Platypus imprinted in dark blue a few times. At the hose top is a connector to the translucent bite valve. The bite valve has a blue mouthpiece and comes with a shut-off. I turn the shut-off to on, bite onto the mouthpiece and a narrow plastic gap opens, releasing water. Once done, I release my bite and the bite valve closes, so there is no leakage at all. It is not even necessary to turn the shut-off. I often only close the shut-off when I store the backpack with the filled bladder on my car's backseat on the way to the trailhead, or when I keep my pack resting sideways in my tent at night. Attached to the hose is a handy black plastic, silver metal clip on. It allows me to attach the bite valve end of the hose to my backpack's shoulder strap.
the bite valve with a handy clip-on

insert the hose end into the bladder connector

Near its top, the flat, empty bladder width is 8.7 in (22 cm), while near its bottom it narrows to 7 in (17.8 cm). This narrowing shape makes it a bit easier to insert the water-filled bladder into my backpack's hydration sleeve. From the top of the slide-on seal to the bottom, the bladder measures 17.2 in (43.7 cm). The polyurethane is non-slippery, so usually I have to use my flat hand and press-guide the bladder into the narrow sleeve. I used to own a 2 L (70 fl oz) hydration bladder and that usually easily slid into the sleeve.

While 3 L (100 fl oz) fill capacity mean that those are also 3 kg (6.6 lb) of weight, I purposely selected this large size for carrying a lot of water on desert outings or trips where we may have no chance to refill for a long distance. In those cases, I would have to carry the weight anyway and I don't like carrying numerous bottles. And of course, I can also simply fill in less than maximum.

When I get ready for a trip, I fill the Platypus bladder at home and easily push the Slidelock across the zipper. Before I insert the bladder into my backpack's hydration sleeve, I first insert the hose end through my pack's H2O hole in the fabric. Then I pop the hose end into the bladder connector and now I push and slide the bladder into the sleeve. For a filled bladder, a bit of coaxing is necessary, as that filled size just about maxes out the sleeve size of my pack.

When on an outing, I typically do not pull the entire bladder out. I simply pull the bladder out two-thirds, open the zipper and filter into the wide open mouth.

Overall I am fully satisfied with the Platypus Big Zip LP Reservoir. My only complaint is that the blue imprint that I use to measure the fill level very quickly started to fade. The number 3 of the 3.0 L mark is practically all gone. On the 2.0 L mark, the .0 L is almost all faded. The fill level is very important information and I would hate to loose the information. I will soon have to handwrite the info on with a permanent marker.
the water level imprint faded too quickly

I looked up the manufacturer's warranty information on their website. Cascade Designs (doing business as Platypus) warrants its products to be free from defects in materials and workmanship for the useful life of the product. They do not cover wear and tear and among their examples for wear and tear is faded colors.


Idlehour Trail Camp, Southern California, USA
April 2017
2 day/ 1 night backpack 17 miles (27 km)
Elevation: 1300 - 4600 F (400 - 1400 m)
Temperature: 53 - 69 F (12 - 21 C)

Mission Creek Car Camp, Southern California, USA
April 2017
2 day/ 1 night car camp with 7 miles (11 km) day hikes
Elevation: 2500 ft (760 m)
Temperature: 61 - 90 F (16 - 32 C)

Lone Warrior Point, Southern California, USA
April 2017
2 day/ 1 night backpack 15 miles (24 km)
Elevation: 5800 - 8700 ft (1800 - 2650 m)
Temperature: 42 - 68 F (6 - 20 C)

Arizona, USA
May 2017
7 day vacation with day hikes and Grand Canyon rim-to-rim 24 miles (39 km)
Elevation: 2500 - 9000 ft (760 - 2740 m)
Temperature: 50 - 90 F (10 - 32 C)

Yosemite National Park, California, USA
July 2017
4 day/ 3 night backpack 19 miles (31 km)
Elevation: 4400 - 7200 ft (1340 - 2200 m)
Temperature: 60 - 90 F (16 - 32 C)

Marion Mountain, San Jacinto State Park, USA
July 2017
3 day/ 2 night backpack 14 miles (22.5 km)
Elevation: 4700 - 10320 ft (1430 - 3145 m)
Temperature: 51 - 65 F (11 - 18 C)

This is just a selection of three-season outings that I used the Platypus Big Zip LP Reservoir on. I did not use the Reservoir in freezing conditions, so I cannot report on its performance with winter temperatures.


The Platypus Big Zip LP Reservoir is my trusted hydration resource on dayhikes and backpacking trips.

Does NOT leak
Bite Valve can get switched to off position
Handy clip on
3 L (100 fl oz) go a long way

The very important water fill level blue imprint very quickly started to fade and some numbers are already all worn off/ faded.

Marina Batzke

This report was created with the Report Writer Version 1. Copyright 2017. All rights reserved.

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Reviews > Hydration Systems > Bladders > Platypus Big Zip LP Reservoir 3 L > Owner Review by Marina Batzke

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