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Just Add Salt: PURE Device Purifies Water Chemically

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[leadin]Salt and water fizzle in an electrical bath, a white froth bubbling up. I’m holding a purifying device, my container of lake water ready for treatment on the ground.[/leadin]


A chemical reaction takes place before my eyes, molecules swirling, colliding, creating a new compound inside a tiny slot on the handheld unit.

New this year, the PURE Electrolytic Water Purifier is distributed by Potable Aqua and sold retail for $119 as the “smallest and most cost effective water-purification device” available. Its base technology, an electrically-regulated chamber that converts briny water into a microbe-killing solution, has been around for years.

But the Potable Aqua device offers a new design and upgrades to a product with roots in municipal water treatment as well as military-backed labs.

White froth signifies start of the chemical reaction

Years ago, funding for development of the technology came from sources including the U.S. Defense Advanced Research Projects Agency (DARPA). In the outdoors industry, Mountain Safety Research of Seattle brought to market the Miox Water Purifier, a similar device, beginning over a decade ago.

The Miox product is no longer for sale. But with the PURE Electrolytic Water Purifier you get the same result — a small, battery-enabled unit that manipulates the molecules in water and table salt to create a mixed-oxidant disinfectant of sodium hypochlorite with trace amounts of hydrogen peroxide.

Field Test

Sounds complex, I know. But in use the device is easy — you pour in a few drips of salt water (there’s a container to make brine from salt, which you carry in the device), press a button to select quantity, then hold the same button to begin the reaction.


It takes a few seconds for the salt water to fizz and change. Pour that solution into suspect water and Potable Aqua claims it disables viruses, bacteria, and protozoa, including giardia and cryptosporidium.

Like chemical tablets, including iodine and Potable Aqua’s Chlorine Dioxide product, you must wait to drink. The solution takes a minimum of 30 minutes to work, and you need to wait 4 hours if cryptosporidium is a concern.

Over the summer, I tested the device camping and backpacking with water from lakes and streams. A chlorine smell rises from the device as salt water is converted to its microbe-disabling state. But like most water-purifying products it’s hard to know what’s happening, as the magic is all on the molecular scale.

Dirty Water

Potable Aqua markets the compound as “capable of purifying even the dirtiest of water,” no need to filter. But for cloudy water I recommend at least filtering through a shirt or cloth before treatment to remove the chunks.

You charge the PURE unit at home, and its internal battery is cited to provide power for 150 liters of water-purification work. On back, the company built a tiny solar panel capable of recharging the device in the field.

Solar panel on back

Potable Aqua claims the PURE will treat more than 60,000 liters of water over its lifetime without replacement parts. It weighs a scant 3.8 ounces and is durable enough to toss in a pack.

Niche Market

The device seems to work. So far, I haven’t gotten sick, and the chemical process that kills waterborne nasties is well founded.

But with many good water-purification methods on the market, a process that requires a long wait (30 minutes minimum) before imbibing is limited in use. For example, for much less money you can pick up a Sawyer Mini filter ($25) that will remove most all the hazards found in most North American surface water.

Pump-based filters offer a faster way to get water, but in most cases they do not disable viruses, which may be a concern when traveling overseas. Filters are also not great if you need large quantities of water, as they require a lot of pumping to get a few liters of drinkable water.

Potable Aqua notes its solution has attributes not available from other methods. It can better inactivate microbes inside and outside of the container, including on the threads of a cap, a lid, or drink spout, and it also serves as a residual disinfectant, the company claims, to “help protect water for later use” in the same container.

Perpetual Water

But the main appeal might be that with just a little salt you can make drinkable water nearly indefinitely.

Its solar panel makes the PURE self-sustaining, and, once fully charged, the little unit will treat large quantities of water, up to 20 liters at once. For disaster preparedness or possible large scale use like at a basecamp, that is a major distinguisher.

A single button and LEDs provide simple user interface

It costs $99 at REI and other sites (msrp is $119). Look into the PURE unit if you need a way to obtain lots of drinkable water from a suspect source, or if you need an emergency backup that will make nearly unlimited water from a shaker of salt.

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