Local companies are continuing to quench Japan's thirst for Hawai'i bottled water, with exports up 4.5 percent during the first half of this year.

Export numbers released by Foreign Trade Zone No. 9 show about 40.5 million tons of water were shipped to other countries from Hawai'i during the first six months of the year, up from 38.7 million tons during the January-to-June period last year.

Much of the increase is attributable to the boom in desalinated deep-sea water and its expanding market in Japan. There and in other Asian markets the water is marketed as a nutrient-rich, pathogen-free, natural product drawn from pristine ocean waters thousands of feet below the sea surface. The market has grown dramatically in recent years and water has become one of the state's biggest export products.

"Water started from nothing a few years ago," said Gregory Barbour, who tracks water exports as administrator of the foreign trade zone here. He said water is now among the top five exports to foreign countries from Hawai'i.

A number of companies have sprung up to fill the market, including Pure Pacific International Inc., which started Big Island spring water as well as desalinated water in recent weeks.

Other companies catering to the export business include Koyo USA Corp., which draws water from 3,000 feet deep at the Natural Energy Laboratory on the Big Island, and Hawaii Deep Blue water in Honolulu, which draws water from about 2,000 feet below the surface several miles off O'ahu.

Koyo markets its water under the MaHaLo Hawaii Deep Sea Water label. It says its Kona plant is the world's biggest deep-sea bottling facility, able to turn out 750,000 bottles daily.

Barbour said the export numbers do not paint a complete picture for the state's water exports since some is shipped to California before being transported to Japan and Asia. Barbour said he suspects some of the Hawai'i-produced numbers are included in California's export numbers.

But even without adjusting numbers for this, Hawai'i ranks as the second-biggest water export state in the country, just behind California.

The export figures also show Japan is the top destination for water exported directly from Hawai'i, followed by China, Hong Kong, Palau and Taiwan.