Some of the planes had 'dual store' capability, i.e. the option to carry two drop tanks under each wing. Normal patrol flights would return with the empty tanks, as they could be refilled. Thus it would appear that all of the fuel tanks so far found in Micronesia are 120 gallon combat tanks, which were dropped off as part of training exercises. These drop tanks were made by a variety of manufacturers on behalf of the USAF, among them Japanese companies such as Shin Meiwa. The atolls of the Marshall Islands are made up of small islands with very small ground water lenses.
Rainwater catchment is a priority and any suitable receptace is used as a water tank.
Thus it is not suprising that the drop tanks were utilised as water catchments. Note the guttering from the roofline. A survey on Mejatto Island, Kwajalein Atoll, encountered a drop tank used as a water catchment. The tank had been found washed ashore on Rongelap Island, Rongelap Atoll, and moved to Mejatto Island on Kwajalein Atoll when the island population was evacuated in 1985 due to radiological contamination. A drop tank found at the shore near an abandoned house site on Ebon originally came from Majuro Atoll.