U.S. Navy

Distilling Ships (AW)

Before modern reverse-osmosis desalination made warships self-sufficient in fresh water, the Navy needed dedicated ships to produce it. Four distilling ships — two converted from water barges, two from larger hulls — operated at forward Pacific bases during World War II, turning seawater into the fresh water that kept entire task forces and invasion beaches supplied. At their peak, the larger AW ships produced over 120,000 gallons per day. Essential, invisible logistics that most histories never mention.

Pacific Water Supply 1943 - 1946

AW-1 — First Distilling Ship

Converted from a YW district water barge, Stag was the Navy's first purpose-designated distilling ship. Small and ungainly, she carried evaporator plants that could turn seawater into fresh water for ships and shore installations that had none. At forward Pacific anchorages where no infrastructure existed, Stag anchored and became the water supply for an entire task group. Without her, men drank what they could catch in tarps when it rained. Read more

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AW-2 — Barge-to-Ship Conversion

Sister ship to Stag, Wildcat was another former water barge pressed into ocean-going service as the Pacific campaign stretched supply lines beyond anything prewar planners had imagined. These small ships were never designed for open ocean transit, but the need for fresh water at newly captured atolls overrode peacetime engineering concerns. Wildcat's crew operated distillation equipment around the clock in equatorial heat, producing water that tasted of minerals and machinery but kept thousands of men alive. Read more

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AW-3 — Large-Hull Distiller

Named for the Pasig River in Manila, this larger distilling ship represented the Navy's recognition that water production needed to scale up with the invasion force. Converting bigger hulls with industrial-grade evaporators, Pasig could produce over 120,000 gallons of fresh water daily — enough to supply a Marine division ashore on a contested island. She operated at forward bases where the only alternative water source was often contaminated by combat, decomposition, or Japanese demolition of local infrastructure. Read more

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AW-4 — Fleet Water Factory

Named for a river in the Philippines, Abatan was the last and most capable of the Navy's distilling ships. At Okinawa, where hundreds of thousands of American troops fought a brutal island campaign, ships like Abatan anchored offshore and pumped fresh water to the beach through floating hose lines. The alternative was purification tablets in shell craters. Abatan made the difference between a force that could sustain operations and one that would collapse from dysentery and dehydration within weeks. Read more

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4

Distilling Ships

120K+

Gallons/Day Peak

Pacific

Theater of Ops

AW

Hull Designation