Water samples are being drawn from the Aiea gulch well more than 200 feet down below the surface.
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They will be sent to a lab on the west coast to ensure that our drinking water is petroleum-free.
"We want to make sure water is safe to drink and our customers are safe and the water is going to be good for a long period of time," said Board of Water Supply quality control administrator Erwin Kawata.
In his 30 years with the Board of Water Supply, Kawata could only recall one other time when the city shut down a Central Oahu well because of pesticides that made their way into our water system.
The contaminants were from soil fumigants used by the pineapple industry in the 1940s.
"Since that time nothing as significant as this," Kawata said.
In a rare event this month, military brass sat shoulder to shoulder with city and state officials to address the possibility that thousands of gallons of fuel from massive underground tanks may have leaked out.
But Kawata says the Board of Water Supply has question of its own about whether the military's monitoring systems are adequate and whether enough is being done to protect our valuable resource.
If the wells that supply much of Honolulu get contaminated, what then?
The Board of Water Supply currently uses chlorination systems to provide clean drinking water to customers.
It says its experience of using carbon filters to get rid of the pesticides in Mililani's water wells could be applied if fuel from the Red Hill storage tanks ever gets into our aquifer.
"We were one of the first utilities in the United States to apply it on a large scale. Prior to that it was done in a small scale, but we applying it to millions of gallons," Kawata said.
But there is a price to pay once contaminants get into our water source.
With no end to the monitoring and filtering, there is this sobering fact to face
"We will continue to do so into the future. In many of the cases some of the levels of contaminants have actually increased over time," said Kawata.
If there were to be a mass petroleum release and our water source is affected a contingency plan filed with the state health department calls for either treating the water -- finding another water source or something alarming: water rationing.