Kokua Line

June Watanabe

Board uses only
chlorine in water supply

Question: I live in Mililani and notice a chemical taste to our water. What's happening? Is the Honolulu Board of Water Supply putting more chemicals in our water? If so, why? How do we know if it's safe to drink?

Answer: The Board of Water Supply says it does not put any chemicals in its water, although it does chlorinate about 50 percent of its supply, including the water in Mililani.

"There have been no changes to the sources providing water to the Mililani community, nor has the board changed its testing and monitoring methods," said spokeswoman Wanda Yamane.

The agency has been chlorinating part of its water supply -- specifically, water that has gone through a "granular activated carbon" treatment -- since the 1980s, following the big pesticides scare, she said.

The treatment was "one of the remedies to purge the pesticides in the water" and is used to make sure "there's no question as to the safety or quality of the water," Yamane said.

"Because we are able to transport water all over the island, there are days when some communities receive no chlorination in their water, some days where they will get a little," she said. "It depends on what sources they obtain water (from) that day."

Your complaint is the only one the board has received about a chemical taste, she said. Yamane speculated you may be referring to a chlorine taste, but without more details, she said it was difficult to answer your complaint.

She asks that you contact the agency directly (7:45 a.m. to 4:30 p.m. weekdays at 748-5000) and give details about the taste, how often you detect it and where you live.

People shouldn't be able to tell the difference between chlorinated and unchlorinated water, Yamane said. Because the amount of chlorine used "is so small and put in at the source, rather than within the distribution system, they're not supposed to be able to detect it."

So it is a concern when people call and say they smell swimming-pool water from the tap, she said.

The Board of Water Supply says it does not have to use chemicals because it receives its supply from rainwater, which "percolates slowly down toward the basal aquifers" and is "purified naturally by the volcanic rock."

Other communities get their drinking water from surface water sources -- lakes, rivers or streams -- that require treatment with heavy chemicals to make it safe to drink, according to the agency.

As for safety, the board says regular testing results "show that our water complies with all federal and state standards."

Meanwhile, the federal government now requires all community water systems like the Board of Water Supply to provide a yearly water quality report. The reports were mailed out in May and June this year, Yamane said.

To request a copy, call 748-5370 or e-mail Or, you can get one quicker by visiting the agency's Web site, Double-click on "Water Resources/Quality," then on "Water Quality Report," then on "Consumer Confidence Report." By entering your address, you will be able to see your water quality report and print a copy.


See the Columnists section for some past articles.

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