Persian Gulf water is saltier than water in the open sea but is still a valuable military asset because it can be purified for culinary uses - outside of areas tainted by the oil spills.
One of the first reserve-component military units called from Utah to participate in the Persian Gulf military buildup was a 14-member water purification detachment from the Utah Army National Guard.The 120th Quartermaster Detachment arrived in Saudi Arabia in mid-September and almost immediately began purifying water from a bay on the Persian Gulf.
Bottled water has been the main source of drinking water for U.S. and allied troops in Saudi Arabia, but the water purification equipment and operating teams have provided a backup supply and water for laundry and other needs.
Purifying gulf water is a complicated procedure, requiring double treatment in the reverse osmosis equipment operated by the Utah National Guard, and it is also very expensive and pushes the equipment to the limits of its operating capacity.
So while the oil intentionally dumped into the Persian Gulf by Iraqi forces does not threaten the primary water supplies for allied troops, it does pose a threat to secondary supplies, depending on how far the oil slick spreads.