A Platy Bottle and a Platypus Hoser with almost-frozen water warming in the sun
A Platy Bottle and a Platypus Hoser with almost-frozen water warming in the sun
Em enjoying a well-deserved sip above Crabtree Meadows.
Em enjoying a well-deserved sip above Crabtree Meadows. Mt. Whitney in the distance.


The big conundrum, oh, the eternal question: how do you carry thy water? Soft bottles? Hard Nalgene? Aluminum? Hydration bladders? Goat skin?

As I mentioned this several times before, I never did any real backpacking when I was a kid, but I went hiking and camping a lot. I always hated looking for the water bottle and drinking from it. We had no access to anything like a hydration bladder, but later, when I first learned of their existence, the idea of being able to access my water this easily appealed to me right away.

Again, there are many choices, we settled with Platypus and within that, the Hoser. It was the lightest, the simplest design, and everybody hailed it as really durable. Their Big Zip is supposed to be equally good, but it's heavier, and the extra closure on the other end makes for an additional part that can break or leak.

The Hosers come in several sizes, from 1 liter to 3 liter. We chose the 2 liter size as the 1 liter seemed too small and the 3 liter too excessive. Also, the 3-liter would not have fit the hydration sleeve our backpacks. Yep, another aspect you need to check for.


The Hoser is deceptively simple, yet very well engineered: it's a big, sturdy plastic bag. One end has a small attachment loop of hardened plastic. The little clip at the top of the backpack's hydration sleeve goes here to prevent the bag from collapsing when it's getting empty.

The other end has a screw-closure at an angle, with a hose attached to it. The end of the hose comes with a bite valve. There's also a clip on the hose to secure it to the backpack. It prevents it from bouncing around, and actually, we secure the bite valve, too as it can fall off sometimes. More about this later.

The interior of the bladder is made of food-grade plastic with silver-ion to protect against bacteria and mold. In practice, this means that it will never rot on you if kept reasonably clean. I can attest to this, it never happened to us.

Then there's the valve cover. This is extra and it's pretty expensive for what it is, but it's worth it. When first testing the Platypus, I quickly realized that the valve can get dirty very easily as I'm really clumsy with such things. The valve cover solves this problem, though there's a bit of a learning curve on how to set it up correctly.

Filtering with the Sawyer Mini from one Hoser to the other
Filtering with the Sawyer Mini from one Hoser to the other

How much water?

Water can be by far the heaviest item you're carrying, so you want to make sure there's not too much of it. However, at the risk of stating the obvious: you're friggin' dead without it.

Always err on the side of caution. It happens pretty often that hikers get in serious trouble because of dehydration. Hardcore ultralighters sometimes carry almost no water, and that's OK if you know the terrain, your abilities, and what awaits you. Just don't be overconfident with this.

I always try to do as much research as possible and fill up accordingly. Look at the map, talk to the rangers, ask hikers coming our way, etc. Sometimes we have as little as half a liter or less - if the weather is not too hot, there's lots of water along the trail, etc. Not carrying anything works, too, but then it takes more time to get water from the stream if you need to filter it.

We don't really like going to places with no water, but it happened a few times that we had a full gallon extra in our backpacks (oh, so heavy) because we knew we'll be without a water source for over a day.

Most of the time, on a regular day in the Sierra, we have around a liter each in the morning so we can get to lunch without having to filter. After lunch, we put in another liter-ish, depending on conditions.

Pack and Use

First of all, I always check for leaks after filling the bladders. I turn them both ways and apply a bit of pressure to see whether everything is tight. Then I make sure the outside of the bladder and the hose itself are as dry as they can be. Most of the time, I wipe them with a towel or my shirt.

The Platypus is always the first item that goes in the backpack. The way our packs are, that's the best method to pack them. The reason for the above-mentioned wiping is that any moisture in the enclosed space of the hydration sleeve can lead to mold very quickly. Having the interior or the backpack rot is not a very good thing. By making sure it's always dry, we never had a problem with this.

The hydration ports on our packs are not big enough to fit the valve with the cover, so I always blow back any water from the hose, then take the valve assembly off, feed the hose through the port and the little accessory loop on the pack's shoulder strap, then put the valve assembly back. If there's nothing else in the pack and I'm not a complete idiot, I can do this without spilling any water.

Em drinking from the Hoser in my pack
Em drinking from the Hoser in my pack

The valve can fall off, even if it was put on properly. It doesn't happen very often, but it can rub against something or you can tug on it by mistake. We never lost one, but I can imagine how anoying that must be. To avoid this, we secure the valve cover either with the little clip is comes with or sometimes I attach it with a tiny carabiner to the lanyard of the inReach.

The bite valve is easy to operate and after a while, it becomes second nature. However, drinking from it when out of breath is way more difficult than from a regular source. Conversely, if both the pack and the bladder are really full, so much pressure can be on the bladder that water starts squirting into your mouth as soon as you bite down on the valve even a bit. In these cases, watching out for the valve falling off is really important as you can lose a lot of water very quickly if it happens. Tip: lean back. This will take pressure off and the water will stop flowing.

By the way, Em really hates drinking while walking, even when she's not out of breath. It just doesn't work well for her. We always stop for a moment, take a few deep breaths, then drink.

Another very helpful trick is to blow the water back after drinking. Water left in the hose can become stale, hot or even freeze, plus when you blow the water back, you'll feel it bubbling against your back, and after a while, you'll get good at estimating how much you have left.

Refilling without unpacking the backpack is not easy, but it's doable. We try to avoid it if possible, for example if we know that we only got another hour left to walk, but we're out of water, we put some in an external soft bottle and strap it to the top of the pack.

However, it's not that big of a deal. I always make sure the side compression straps are open, then remove the bear canister, if any, and there's a technique how to lean the backpack forward and slide the bladder in there while moving the other items' pressure out of the way.


In the backcountry, we make sure we rinse the Hosers at least every few days with a bit of filtered water. As soon as we get home, I wash the bladders, the hoses and the valve assembly very thoroughly with really hot tap water, but never with any soap. To prevent mold in the valve and/or the valve cover, we soak those in water with some baking soda.

After washing, we always make sure they dry completely and store them hanging in the bathroom. Before use, another rinse with hot water.

This - and my stupidity - led to the leak
This - and my stupidity - led to the leak


We bought two Hosers in 2011. Two years later, on our Trans Sierra trip, we got into that nice little storm I keep mentioning here and there. Weather forecast was 20% of rain, but then it hailed for 45 minutes and rained like crazy for over an hour. Before the storm, we prepared for dinner, and soaked some rice in a small Ziploc bag. When the bad weather hit, we decided to have cold dinner, and in the big excitement of shoveling the hail from the trench around the tent (to keep the water flowing) and all the other preparations, we forgot about the Ziploc with the rice. It stayed outside our tent in the vestibule, with an empty Hoser on top of it. During the night, we heard some rustling, it sounded like a mouse is foraging around our vestibule. We did not think that there actually anything edible there. After we shook the tent a few times, the mouse went away and we fell asleep again.

Of course, the smart critter was eating the pre-soaked rice, as we found out in the morning. He chewed a whole in the Ziploc and ate a bit of the goodies before being chased away. Unfortunately, as the bladder was right there, somehow he got a tiny bite into that, too. When I filled it up, I realized there's a small leak on the side, close to the screw-top.

In this case this was not a big issue, it was the last day, we were 12 miles from the trailhead and there was ample water on the way, so we simply put some more water in my bladder.

We fixed the leak with a small piece of vinyl patch and it's holding up to this day (writing this in 2017). We use it as extra bottle or as the holder for the dirty water when filtering inline with the Sawyer Mini.

The other old Hoser gave up after about five years of use. Again, it was pretty much my fault, I used it as a dirty water bag and applied too much pressure, not realizing that our filter would desperately need a backwash. The seam burst on the side.


Hands-down the best hydration bladders. Light, simple, and unless you do irresponsible things, like me, almost indestructible. Same great quality as with the other Cascade Designs family of products. Take a look at our review of the Thermarest mattresses and the PackTowl towels.

Preparing to put the Hosers back after lunch break at Gallats Lake
Preparing to put the Hosers back after lunch break at Gallats Lake