In the late 1990s, a team of Singapore engineers visited a California water purification plant called Water Factory 21 and were struck by its three- step process.
This involved microfiltration to sieve out bacteria, reverse osmosis to remove chemicals, and ultraviolet purification.
That process helped to inspire Singapore's Newater reclamation process. And the agency that pioneered it, the Orange County Water District in southern California, has now clinched the Lee Kuan Yew Water Prize for its innovations in managing water.
The county water district will be awarded the sixth edition of the prize at this year's Singapore International Water Week in June, said Mr Chew Men Leong, chief executive of national water agency PUB, yesterday.
Mr Chew lauded the Californian agency for its work in groundwater management and water reclamation using advanced technologies, for its public outreach on water issues and for advancing public acceptance of water reuse.
"The Newater model came largely from them," he said.
The agency was picked from 45 nominations from 24 countries.
Winners of the award receive $300,000, a certificate and a gold medallion.
The Orange County Water District manages a large underground basin that supplies about 70 per cent of water for 2.4 million people in arid southern California.
In 1976, it started Water Factory 21 as a reliable source of water, and used the potable reclaimed water to prevent seawater intrusion at the groundwater basin's coastal edge.
In 2008, the agency began using reclaimed water to refill the basin, and also uses water from the Santa Ana River and storm flows, as well as imported water, to do so.
Today, other cities from San Diego to Singapore have expanded their use of reclaimed water for indirect potable or non-potable use.
"We see used water as a resource," said the Orange County Water District general manager Michael Markus.
He said: "We need to get more than one use out of our water."
Now, amid California's most severe drought in decades, the agency intends to build a US$142 million (S$179 million) expansion to the current groundwater replenishment system by 2015, he said.
Just US$1 million of that came from grants. The rest was funded by loans and water tariffs, he added.
Previous winners of the prize include Canadian researcher Andrew Benedek, for his work on water treatment membranes, and China's Yellow River Conservancy Commission, for its river basin management.
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