A Pint’s a Pound the World Around

a pint's a pound the world around
| October 20, 2015
Categories: Assorted Ramblings


“A pint’s a pound, the world around.”

This old rhyme has a few different meanings dating back to ye olde’ medieval Britain, but it also goes to illustrate how heavy water is. Sixteen fluid ounces of water isn’t much, but it sure feels like it when you have to carry it over distance. The ability to reduce the weight you have to carry in the field is as important to a pipe-hitter doing JCET missions in Africa as it is to the adventuresome solivagant out along the Bibbulmun Track.


Grunts: solivagant.

Think about it like this. One full gallon is 4 quarts, or 8 pints — that’s 8 glasses of beer (6 if you’re drinking the homebrew at Nancy’s Squat’n’Gobble).

If you’re at the pub, this would make for a great night, some terrible decisions and (quite likely) an awful hangover. But if you’re in the heat of the desert and active, a gallon won’t last you long. One gallon of water weights 8 pounds, and the more you carry on your person, the more you need it to stay hydrated. For those conducting combat operations in arid climates, it’s not uncommon to consume more than five gallons a day just to stay alive. Sometimes a grunt will carry more weight in water than he does in ammo, fearing the lack of resupply. For this reason, specialized units around the world have used water purifiers for years to cut down weight.

When operating in areas with abundant water sources such as streams, creeks, lakes and rivers, it’s almost a no brainer for a reconnaissance team or long range patrol to bring a filter along and eliminate the need for water resupply. The lighter you are, the faster and easier you can move. Today we look at a viable option for field water purification, the GravityWorks system from Platypus.


The complete kit.

Platypus is a company that has specialized in hydration bladders for as long as we can remember, and we’ve used their products in the past with great success. The company was absorbed by Cascade Designs some time ago and their line continues to be produced under this banner. Their newest product is called the GravityWorks, and is an extremely light and portable means of filtering clean drinking water. 

Platypus produces two variants of the GravityWork:, a larger a 4.0 L system, and a smaller 2.0L system (we tested the smaller one for this article). The 2.0L system is incredibly light, weighting in at only 10.75 oz for the entire package. This weight is something to note, because that means the kit weights less than a single glass of water. The weight savings over packing bottled water are obvious, as you can refill your bottles or hydration bladders while on the move. 


Filling the reservoir is quick and easy.

The kit comes rolled up and stowed in its own mesh storage bag, and is small enough to fit into a cargo pocket. The system is very simple to use, as the user only needs to find a natural source of water, fill the included “dirty” reservoir, and let gravity do the rest. The two liter reservoir is made from a pliable, durable material and features a zip-lock style closure at the top. We filled it numerous times in various streams and creeks over the course of several camping trips by simply prying the top open and dunking it into the water. Once filled, the reservoir can be held or attached to a tree with the included hanging strap. The water filters down through a quick detach tube, and meets the inline filter. The dirty water is forced through the filter under its own weight, and removes bacteria and Protozoa, including Giardia, Cryptosporidium, E. coli, Salmonella and Cholera. For more filthy sources of water, we would pre-filter debris and other contaminants out before filling the reservoir, to avoid clogging the filter. 


Hang the kit up, or hold high IV bag style.

The flow rate is pretty quick, and on our timer we clocked a full one quart filled to the brim in 64 seconds. We also noticed that the cleaner the water, the better the flow rate. The line below the filter has an adjustable shutoff clamp, which serves a couple purposes. When initially using the filter, you need to let water flow through the system and then back-flush the filter to ensure proper function and to avoid cross contamination. This takes about four seconds, and is simple to remember.

The only weak point of this system is the filter itself, which can be damaged from impact or abuse. The filter also must be stored dry over long periods of time, and safeguarded from the cold, or it will crack from the freezing water left inside. This should also be easy to avoid, as the filter element can be pulled from the kit and stowed inside your jacket. Keeping the small, light filter next to your body will help prevent freezing in cold climates, and ensure that it is not damaged as a result. 


The included bottle adapter is nice, but kind of pointless.

In the field, we noticed that the purified water left the down line crystal clear, with no odor. The water also tasted superior to the local tap and well water, which was another perk. We used the GravityWorks to fill hydration packs, canteens and water bottles, and the system worked great with them all. The kit also comes with adapters to fit several sizes of popular commercial water bottles. We found these adapters to be kind of pointless, and would only pack them if we were expecting high winds to blow dust or dirt. Otherwise, the adapter just takes up room and adds weight to an otherwise small and light system. 


Overall, we really like this kit. The Platypus GravityWorks is a well thought out and relatively durable system. We like that they idiot-proofed it as much as possible, going as far as to print “DIRTY” on the reservoir, and by including a foolproof, waterproof pictogram instruction sheet sewn into the storage pouch. You could be illiterate and still figure it out, which is good for any grunts out there.


The downside? There is no way to know when the filter is spent or damaged. You could jack up the filter, and have no idea you’re drinking contaminated water until it’s to late. This requires you to baby the filter element, and limit loaning it out to careless friends. The price for the system is a little steep as well, but that’s to be expected for a product made here in the states, particularly one that fills a specialty niche in the market. Having used the filter for a few months, it has now become a piece of mission essential gear in our day bags. Thanks to its simple design and good ole’ gravity, it sure as hell beats pumping or carrying water. 

Mad Duo, Breach-Bang& CLEAR!

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  1. John

    There are two types of countries in the World. Those who use metric for everything, and those that have lost a $200 M Mars probe because they mixed up imperial and metric units.

  2. Tcar

    A pound is close enough to 500g and a liter is close enough to a quart. Get over it rest of tthe world. We tried metric in the 70’s and it didn’t stick. Deal with it.

  3. Skipjack

    Listen up. There are only two types of countries in this world. Those that use the metric system and those that have been to the Moon. Nuff sed

  4. Danny

    There are two types of countries: Those that use the metric system, and then those that go to the moon, invent the airplane, the telephone, the INTERNET, the PC, harness electricity, and find water on Mars.

    • Thomas


  5. Steve

    ‘Mericans don’t need no stinkin’ metric. Except for maybe 9mm 🙂

  6. John

    Speaking of “Around the World”, as someone from Europe, I got a headache from all the archaic, non-metric units in this post. When are you Americans going to join the rest of the World in the 19th Century, and switch to metric?

    • Jim

      Hang on a minute, we still use imperial (and metric) here in jolly old Britain…which is also in Europe…

      • John

        Nope, Britain did officially go metric years ago. How could you have missed that, you’re not really British, are you?

      • John

        And, I just took a second look, and I realized that I totally missed the (and metric) part. So, you are still using both imperial and metric, officially? Are you mixing them, or what?

        What would the point be of having two different systems? I’m pretty sure that the imperial system is still around just because some people are using it out of habit, when that generation disappears, so will the imperial measurements.


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