WASHINGTON (Army News Service, Oct. 14, 2003) -- The Army is nearing the end of testing a pump that will make potable water from vehicle exhaust.

Doug Snowdon, an engineer from Hamilton Sundstrand, displayed the two-part pump at the Army's Tank and Automotive Command booth at the Association of the U.S. Army’s annual convention in Washington, D.C., Oct. 6.

"All we're simply doing is recovering the water that's present in the fuel," Snowdon said.

In development for three years, the pumps when fielded may cost about $25,000 each, Snowdon said, adding that they may eventually go on every vehicle in the field.

The biggest benefit will be the reduction on the Army's in-the-field logistics, Snowdon said. Currently the Army is using 40 percent of its supply chain on distributing water in Iraq, he said. By minimizing the amount of water being sent forward, the demand and burden on the logistics tail will be reduced, Snowdon said.

The numbers being tossed around for a soldier's drinking water requirement vary, Snowdon said. It’s anywhere from three to four gallons per day, he said.

How it works is simple: the pump combines oxygen and hydrogen in vehicle exhaust into water.

The water comes about by taking the hydrogen, which is also already present in the fuel, and combining it with oxygen, he said. That oxidation makes water, he said.

Now here's where it becomes complicated. The process involves regenerative heat exchangers, evaporative coolers, filters and pumps.

The vehicle exhaust moves from the exhaust system to a heat exchanger. That exchanger lowers the temperature of the exhaust before it hits those coolers. The cooler is similar to a car's Freon-based air conditioner, said Snowdon. The cooler lowers the exhaust temperature to a point where water starts to condense.

"For us, we run our condenser at about 80 degrees Fahrenheit," he said.

That now-cool exhaust goes back to the heat exchangers on the other side and cools the incoming stream of exhaust, said Snowdon.

From there, the water is put into a small receiver, Snowdon said.

At this point the process isn't done. The last step is chlorination. The system, Snowdon said, uses Miox or a mixed oxidation generator. This generator uses salt, water and electricity to make the water drinkable.

It will also replace the use of iodine to make water potable, he said.

The system is set up on two sides of a vehicle, Snowdon explained. At the booth, a Humvee held the system. The driver's side held the receiver and a small pump. The passenger side had the water treatment parts.

On the passenger's side, the water is brought up through the system's "treatment beds," or filters. A sensor inside the Humvee tells the soldiers when those filters are used, he said.

The filters will produce about 150 gallons of water before they need replaced, Snowdon said.

For every two gallons of fuel, the pump can make about one gallon of water. In other words, if a Humvee's fuel tank is 30 gallons, the system can produce about 15 gallons of drinkable water, he explained.

That one gallon of water can be produced in about an hour of operation, Snowdon said.

The vehicle's temperature determines how hot the water is, said Snowdon.

"If the vehicle is 120 degrees, (the water) is going to be 120 degrees," said Snowdon.

Although the price per system hasn't been fixed yet, the Army would like it to be about $25,000, said Marit Jagtoyen, president of Lexington Carbon Company. Snowdon's company is a sub-contractor for Lexington, the prime contractor for the pump project.

The first vehicles likely to see this system will be the units that need to stay self-sufficient, like the Special Forces, Jagtoyen said.

The water, which Jagtoyen said tasted like distilled water, also meets U.S. Environmental Protection Agency standards for drinking water, she said.

There were two jars of water on the Humvee. One was filled with a black muck designed to show what condensed vehicle exhaust looked like. The other had the finished product, clear drinkable water.

The black water was acidic and when someone said they shouldn't drink it unless they absolutely had to, Snowdon replied: "Uh, I wouldn't drink it."

The pump will enter field-testing next year at Yuma Proving Ground, Ariz., and the Army Surgeon General's office is about to approve it too, Jagtoyen said.

A prototype is also being built for the Army's Future Combat System, she said.

When Jagtoyen first heard about the Army's request to get water from exhaust, it was a pretty "novel" idea. "Most people don't believe it" can be done, Jagtoyen said.