Pukalani resident Sharon Elston said that even though the county has halted use of phosphoric acid, she plans to wait several months before turning on the tap for drinking water, cooking and bathing.

"Nobody knows for certain how long it's going to take for whatever it is (that may have been causing problems) to flush out of the system," she said.

Elston said she suffered from rashes, burning and itching eyes, lung congestion and other ailments that she blamed on the water additive, which also is used in the manufacture of fertilizers, pharmaceuticals and detergents, and as a flavoring agent in soda pop, beer, jams and jellies, and cheeses.

More than 140 other residents have complained to the county Department of Water Supply since June 2001, when a different compound, zinc orthophosphate, was added to the Upcountry water system in response to a federal order to reduce lead leaching from older plumbing.

The department switched to phosphoric acid last year, but the complaints persisted.

The county this month received permission from the Health Department's Safe Drinking Water Branch to use soda ash, or sodium carbonate, which adjusts the pH of water, reducing acidity and resulting in less corrosion within the pipes.

District health officer Dr. Lorrin Pang said yesterday that preliminary study of a possible link between the water additives and health problems revealed that Upcountry residents who traveled to Honolulu or Las Vegas reported that their skin conditions improved within three days of leaving Maui. Likewise, the conditions resurfaced within three days of returning home.

With phosphoric acid no longer being added to the Upcountry water, Pang said skin irritations should begin to clear up this week, leaving little time to study the situation.

"We need to document the nature of these rashes before they disappear for good, in case the use of phosphoric acid additives is reconsidered in the future," he said.

Pang said one theory is that phosphoric acid may not be directly responsible for the skin irritations. Instead, the compound might be acting as fertilizer for as-yet unidentified microbes, or germs. He said water samples have been taken and frozen for future study.

Pang noted that soda ash will slightly raise the sodium level in drinking water, but that residents on low-sodium diets need not be overly concerned.

"Soda ash will increase one's daily sodium intake by only about 5 percent based on drinking eight liters of water a day. For those watching every milligram of sodium, this incremental rise will be about 100 mg, about half a snack-size package of potato chips," he said.

Anyone with sodium concerns can compensate by lowering sodium intake from salty foods by an equivalent amount or by drinking bottled water, Pang said.

For further information, contact the Maui District Health office at (808) 984-8200.

Water department spokeswoman Jacky Takakura said yesterday that the effectiveness of soda ash in reducing the lead problem will be monitored by additional testing and flushing of the system. Residents may request free lead testing by calling the department's lab at (808) 270-7550.

She said a community meeting to discuss the recent developments is tentatively set for July 19 at a location to be announced.