Filtration plant taps
Kauai’s rainy spot

A new system will pump up to
3 million gallons of water daily

Kauai County and Grove Farm will soon turn rainwater into drinking water using both new and old technology just a couple of miles from what is considered the wettest spot on Earth.

A new, technologically advanced $8.2 million water filtration plant scheduled to open within the next two months will furnish two of Kauai's fastest growing communities -- Lihue and Hanamaulu -- with up to 3 million gallons of water per day.

But the plant will get its water using some old-time technology -- an existing system of waterworks, built perhaps 100 years ago, that divert the rain that falls in the Mount Waialeale area and flows into the Wailua River. The waterworks then carry it to the plant at the Kapaia Reservoir.

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The ditches, concrete water diversions, and reservoir were part of the irrigation system "originally designed to facilitate growing sugar," said Edward Tschupp, director of the Kauai Department of Water.

Some of the system is even used today, as groups of visitors tour the cane fields by floating through the ditches on inner tubes.

Their presence shouldn't affect the quality of the drinking water, Tschupp said. In fact, "the responsible, environmentally conscious tour operators" might even be beneficial, keeping an eye on the system and keeping feral pigs away.

In any event, "the (membrane filtration) treatment technology is very robust and will take out any pathogens from pigs and humans," Tschupp added.

The system, he said, works like a giant sifter, with water from the reservoir being pulled through a membrane by a vacuum. The membrane has microscopic holes that allow the water through and keep out all but the tiniest of particles, Tschupp said. From there, the water will be piped to the water department's Lihue-Hanamaulu water system where it is treated.

The new facility came about because Grove Farm, which bought much of the former sugar cane lands in the area, had to build a 1-million-gallon-a-day treatment plant as part of the agreement to build their new housing developments.

The county, Tschupp said, suggested they build a 3-million-gallon-a-day plant. The county would then buy the treated water to pay for its share of the building and maintenance costs. After the expenses are recouped, the county will take over the plant.

Tschupp said it's a great plan for Kauai to use surface water, because water levels in the county's wells are dropping as agriculture is replaced. Digging more wells is costly, and surface water is plentiful so close to Mount Waialeale, one of the wettest spots on the planet.

"We expect there will be significant cost saving in the future," Tschupp said. "There will be long-term saving for all our customers."