Every trip into the backcountry requires you to either carry all the water you will need for the duration or to purify water along the way as need … and IF available. So, it’s good to know how much you will need for any specific length of trip. This tells you:
- how much you need to carry, and as such how much that’s going to weigh
- how much you need to filter, which might inform decisions such as what filter to use
- how much you need to treat, indicating how much treatment you need to bring
- how much you need to boil, which translates into how much stove fuel and maybe your stove choice.
Calculating Water Needs
Most references agree on the necessity of about two liters of water per day. This does not take into account water loss from exercise, work, or heat of the environment. But you can calculate that too. Most healthy adults at rest should consume 8oz for every hour of the first 10 hours of the day.
Don’t pound 8 oz every hour. This can be counter productive, especially if you are already mildly dehydrated. Sip the amount over the 1 hour period. The gulping method could lead to acute overload and then elimination. The body perceives you are fluid overloaded and wants to bring you back to stasis.
To avoid dehydration during exercise, you can get more accurate calculations using the “Galpin Equation.” “Galpin” is Dr. Andy Galpin. He didn’t name the equation or even actually develop it. As an inside joke, Professor Andrew Hubberman named it after him. Listen to the podcast here.
The Glapin Equation:
Your body weight in pounds divided by 30 equals the number of ounces of water you should consume every 15-20 minutes. This replaces the 8oz:1-hour protocol.
The military has done extensive research in this area. They are very concerned about having enough water to keep soldiers working at peak levels.
According to the Army backpacking, or “rucking” as they call it, is either “moderate” or “hard” work. Next they measure “wet bulb globe temperature” (WBGT) which takes humidity into account. This is also referred to as the “heat index.” If you have ever heard of “black flag conditions” that’s a heat index of >90 degrees Fahrenheit.
From that we get fluid replacement guidelines for each heat index and and work category. They also calculate “work/rest” periods.
Back In the Day…
In the past I have relied on chemical solutions, such as:
- “Potable Aqua” tabs
- “Aquamira” drops
- “Aquatabs“
This was an upgrade from my Appalachian trail days method of “drink and hope for the best.” Chemical solutions are somewhat slow but very light weight and treat a lot of water for their small size. I ALWAYS have some of one of these in my kit. It’s faster and uses less energy than boiling.
I’ve also used pumps in the past, like this old school “First Need XL.”
This filter is still made by “General Ecology” [LINK] and is quite bombproof. It pumps fast and has a useful, albeit slow, gravity filtration capability. It weighs in at 2.3 pounds and the filter needs replacing replacing after 180 gallons (550 liters). The filter replacements cost a whopping $75, coming out to $2.40 per gallon!
Moving Forward
For my Wind River Wilderness trip I decided to try something new. That is something small, light, and easier. I’m going to test two filters: the Life Straw Peak Series and the Sawyer Mini.
On paper they are very similar with one marked difference. The Life Straw filters and incredible (compared to the First Need, anyway) 1,000 gallons (4,000 liters). The Sawyer Mini beats that by a factor of 100. It promisses to filter an overwhelming 100,000 gallons before needing replacement. The Life Straw has a replaceable filter. The Sawyer does not allow for replacing the filter.
Why not carry both? I’m not going to need to filter 1,000, much less, 100,000 gallons on a six-night trip. But at only 2oz, I can carry both and test them across the seven days to see which is the most convenient. Whichever one doesn’t make the cut for backpacking can end up in a vehicle emergency kit.
Speaking of vehicle emergency kits, I got a four pack of theses recently at Costco. Filters 1,000 gallons each but does not allow for filter replacement. Nor can they adapt to water containers like their more sophisticated (expensive) twin.
Unboxing
As I unbox these a few things stand out.
The life straw looks like it was designed by Sir James Dyson (he does like things that suck and blow). It’s sleek, simple, modern, all the bells and whistles hidden away. It’s a bit long but still fits on a pack strap or in an accessible pocket.
The Sawyer appears to have been well engineered to function but not to display on your coffee table. It looks more like that hard to get to part on an old diesel tractor engine that never seems to break. It is a bit thicker but shorter and would fit on a pack strap or in a pocket.
The Sawyer comes with a “cleaning plunger,” a drinking straw, and a small (16oz) water pouch.
Put water in the pouch, screw on the filter and drink (squeezing the pouch makes things go faster).
Using a standard plastic water bottle size and thread, the Sawyer and the Life Straw can both be used this way.
The Sawyer’s straw is hard to fit and very tight. Which is good, indicating it would be less likely to fall off and float away in the creek you are drinking out of. But the straw is plastic and I suspect would stretch out and get loose over time if not crack and split. For this reason I’ve already swapped it out for a food-grade silicone drinking straw. The silicone replacement is longer and more flexible, so drinking out of mud puddles will be easier.
Oh! and it fits on the Life Straw too.
Now the Sawyer “cleaning plunger” seems to be an afterthought. Like they made this cool filter and at the last minute someone asked “how do we clean it?” And someone else said, “lets buy some 50mL syringes from a local medical supply, put our name on the side, and put that in the box.”
Result? A hunk of nearly useless plastic (it could be repurposed to irrigate wounds) that doesn’t fit on the filter. So you want me to hold the syringe on the filter, while also plunging water from the syringe through the filter? I’m not saying it can’t be done but…
The syringe could have been engineered to fit onto the filter. Or Sawyer could have supplied an adapter (I tried both their straw and mine to no avail).
I’ll leave the syringe at home and use my mouth to back-blow air and water through the filter.
Bladders or Bottles?
There’s pros and cons to both bladders and bottles, and I’m sure there is endless debate to be found online. Here’s my thinking.
Bladders are convenient
Fill it, close it, put it in the pack, route the hose, drink as you go. Almost every pack on the market these days has a bladder or “reservoir” pocket and openings to route the hose. Several outdoor gear companies sell their own version of water bladders.
I’ve used Camelback, Osprey, HydraPak, Source, and the MSR “Dromedary.”
Camelback used to have problems with the screw closure. I would get them cross-threaded, and could never get them tight enough, leading to leaks. This has greatly improved.
As far as closures and fill openings, I am a big fan of the HydraPak and Source. They have large-mouthed openings and easy to use, leak-proof closures.
Several brands have ‘quick-disconnect’ hoses and or mouth pieces. And there seems to be some standardization. My HydraPak and Source hoses fit on Camelback bladders and vice versa.
The HydraPak and Source bladders readily crossover. In fact they are almost identical. The small differences are more akin to target audience than function. The HydraPak appealing to the backpacking crowd. The Source more appealing to the military (both the real and the “soldiers of fiction”). Update: Source has separate”outdoor” and “tactical” line of products.
Because bladders are tucked away into the depths of the pack or carrier, they aren’t visible. It’s impossible to know how much you have actually drank or how soon you need to refill them. They do tend to carry more water than a single bottle (2-3 liters), but knowing how much you have consumed requires pulling them out of the carrier.
Lastly, bladders can be hard to fill. It can be done with patience, but its not as easy as a ridged wide mouth bottle. Two people make filter pump filling easier. So too having a tree handy near the source from which you can hang the bladder.
Bottles are multi-functional
Bottles come in all shapes and sizes. They can be as small as 8oz and as big as 36oz. Palstic, glass, and metal. There are double walled aluminum versions from HydroFlask and now Yeti. These profess to keep your tea hot or your water cold longer.
Nalgene is the GOAT of water bottles. Again in multiple sizes, colors and decorative art, and small to wide mouthed.
I have a few old Sigg water bottles that look exactly like stove fuel bottles so be careful there.
I’ve never tried “Kleen Kanteen” or any of the glass bottles that were all the rage several years ago.
Measurements on the side allow quick reference to when to refill or how much you have drunk. It also comes in handy for mixing the right amount of water into your dehydrated meals. Mixing powders seems to taint most bladder materials. Not so much the new plastic, glass, and aluminum bottles don’t seem to have this problem?
To drink on the trail you must have them stored in an outer pocket on on the hip belt. Thankfully most packs have these pockets built in as they do the bladder carrier.
I find bottles, given their ridged nature to be easier to fill. In dirty, gritty water I’ll stretch an old (clean) liner sock over the mouth to catch the worst of it. This is something I haven’t quite figured out how to do with bladders. One exception is my MSR Dromedary, which has a ridge wide mouth opening much like a bottle.
Any reason to carry both?
Sure. If you are certain that there will be water “everywhere” you could carry a bladder for use in camp due to the volume of water it holds. This would be empty during your hike. Why? Weight.
The bottle hold less and you can easily eye when it is getting time to refill. The full 32oz water bottle on your hip weighs less than the full 2-3 liters buried in your pack. I have a friend that professes this system to be best.
I haven’t had a chance to experiment yet with the newer gravity filtration systems. These might work perfectly for my friend’s system mentioned above. The hoses are oriented specifically to accommodate gravity feeding, and so would not work well for drinking on the move.
Accessories
With my new new filtration method, and a propensity to make gear as multi-functional as possible, I’ve recently found a few accessories to be very handy if not flat out necessary.
I bought this pack of adapters and hoses from “Source” and this set of quick-disconnect (QD) adapters from HydraPak. Remember above that Source and HydraPak can crossover hoses from one to the other? The QDs work on both bladders.
This QD male end is designed to fit the Sawyer Mini water filter. And yes, due to the standard size and thread, it fits on the Life Straw too.
Now I can attach a hose to a pack mounted water bottle, and a filter to that. There’s the convenience of a bottle that’s easy to reference, and a ready-at-hand, strap-mounted drinking tube.
And I can attach either filter to a hose for in-line filtration on the go, and mount that on a shoulder strap for easy drinking. I can even use my large Dromedary as a make shift gravity filtration system. It’s not perfect, given the side orientation of the mouth, but it does work.
Given all the options I now have, there’s lots to test and experiment with on my upcoming trips. Stay tuned for updates.
