A new type of microfilter will allow the plant to return to using chloramines instead of chlorine as a disinfectant. Only the Upper Kula water system will be affected.

Olinda is the highest of three surface water treatment plants that serve Upcountry. Because of organic matter in the water, the county since 1985 has used chloramine (chlorine plus ammonia) on the Upper Kula line to produce a water less likely to leach lead or copper from homeowners' lines.

In January, the Water Treatment Facilities Division took the plant out of service to install PDVF (polydivinylfluoride) filters.

While the upgrade was under way, Upper Kula customers have been getting water from Piiholo, which is treated with older-style filters and chlorine.

Paul Seitz, chief of the treatment division, said the Olinda project, which cost just under $2 million, will improve water quality and lower costs.

The Department of Water Supply has been criticized in the County Council Water Resources Committee for being slow to push through capital projects. Like other county departments, it has been unable to fill all its engineering positions.

However, said Seitz, the Olinda work was done in-house and in just 3? months.

"I think we're getting better at it."

Seitz said the new membranes will save money two ways.

First, it will cost less in electricity to run the treatment plant.

Second, the department will save on pumping treated water up from Piiholo.

Although no new source has been developed, the new plant can process more water per day.

The Olinda plant, which had been a million gallons a day short of demand in Upper Kula, will now be able to match current demand, with the water coming out of the Kahakapao Reservoir.

Seitz said he doesn't want to mislead anybody about how that affects water available during droughts. The Kahakapao Reservoir can hold up to 100 million gallons of water, but if there is no water coming in, it can run out. Past practice has been to supplement that water with production from Piiholo.

Seitz said he does not have a dollar figure for savings, but when the project was planned, the payback period was reckoned at less than three years. If Maui Electric Co.'s pending rate increase is granted, the payback would come even sooner.

For some years now, the county has been adding microfiltration to the other methods of purifying surface water. (Well water comes in cleaner and usually requires just disinfection, except where active carbon filters are used to remove pesticides.)

The PDVF membranes are better, said Seitz, because they allow the operators to clean the filters with chlorine and they require much less electricity to run.

The PDVF filters require a pressure of only 5 pounds per square inch, compared with 90 psi for older microfilters.

"They will cost a lot less in energy," said Seitz.

Olinda is the first Maui plant to switch to PDVF.

According to the department, once the switch has been made, the only thing customers might notice is "less of a chlorine odor or taste."

Dialysis patients and fish hobbyists need to be aware of the change.

In the dialysis process, water comes in contact with blood across a permeable membrane. Chloramines in that water would be toxic, just as chlorine is toxic, and must be removed from water used in kidney dialysis machines.

The department asks home dialysis patients to contact their medical advisers for more information.

Chloramines are toxic to fish and must be removed from tank water, just as chlorine is toxic and must be removed.

Although chlorine rapidly disappears from aquarium water on its own, that is not the case with chloramines; steps should be taken to remove chloramines.

Most pet stores sell dechlorinating agents and generally recommend using them. Chemicals used to remove chlorine should work just as well for chloramines.

The department was able to take Olinda out of service because demand for water is low during the winter.

Seitz said with the new filters, his division is in better shape to deal with the summer drought than last year.

The dry season usually starts around May 1. Seitz said the storage situation is "typical" for this time of year.

For questions about water quality, call the water department laboratory, 270-7550; Administrative Officer Jacky Takakura, 270-8046; or visit www.mauiwater.org.

For health concerns, call the Maui District Office of the State Department of Health, 984-8200.