When Gen. Erwin Rommel, Germany's famed "Desert Fox," fought the allies in North Africa during World War II, the battles had to be short, or fought near water holes. Even as recently as 1979, when the United States organized the Rapid Deployment Force to safeguard Persian Gulf oil, little military thought had gone into how to provide the massive quantities of water needed by troops deployed for a possible desert war.

Today, after a 10-year expenditure of $420 million by the Army and $12 million by the Marine Corps to close the water gap, Pentagon officials say U.S. troops now in Saudi Arabia will not go thirsty.

Among components of the water supply system that has been carried to the Persian Gulf:

Digging rigs from Oklahoma that sink wells of up to 1,500 feet into the desert floor -- deep enough to strike water in most areas where the troops will be deployed.

Filtering machines -- called Reverse Osmosis Water Purification Units, or ROWPU -- that filter salt out of sea water and mud out of swamp water.

Ten-mile lengths of six-inch diameter hose to take water from tanks in the rear deployment area to troops at forward outposts.

Bladder bags that can be filled with water and deposited by helicopter at remote outposts.

Cooling machines to attach to mobile water tanks, called "buffalos," to reduce the temperature of water from 120 degrees to 60 degrees. "Otherwise the guys won't drink it," said one military water specialist.

The Vietnam practice of dosing uncooled water with Kool-Aid to make it taste better is not being followed in Saudi Arabia "because that's not the kind of water you want to wash out a buddy's wound with," said Lt. John B. Stalnaker, a Marine Corps water expert.

Army water expert Col. Richard P. Holley said the military had modified commercial equipment for field use rather than trying to build a high-tech water system for desert deployment. "The Army didn't go into the skunk works and do anything new," he said in an interview in his basement office at the Pentagon.

Holley said televised pictures of U.S. soldiers in Saudi Arabia drinking bottled water are misleading. Bottled water, he said, is being bought primarily to quench the troopers' thirst while they are traveling from their landing spots to duty stations, where local water is available.

Part of the Army and Marine water systems resembles that used for distributing oil. A seagoing barge carrying thousands of gallons of water anchors in a Saudi port, pumps the water through long pipes into storage tanks on shore and then relies on trucks and helicopters to take smaller loads of water inland to the troops.

The military wants each man working under the desert sun to drink at least four gallons of water a day, and Holley estimated that troops working outside in the Saudi desert probably are drinking between four and six gallons. One danger is that someone on the verge of suffering a heat stroke loses his thirst, officials said, and troops must constantly be reminded to keep drinking water.

Counting the water needed for washing and other non-drinking uses such as cooking and hospital functions, the objective is to produce and distribute 20 gallons for every soldier deployed.

Stalnaker said the Marine Corps prefers to fly water to forward outposts rather than truck it. Helicopters already in Saudi Arabia are equipped to carry 500-gallon drums of water in slings from water-producing units in the rear to troops in remote areas, he said.

But the water-carrying helicopters are slow-moving and extremely vulnerable to ground fire. Dying of thirst on the scorching desert is such a horrible death that military leaders have discussed the need to reach an international understanding to refrain from shooting at any water-carrying vehicles and treat them like ambulances.