Military officials said Wednesday they hope to restore clean drinking water to Elmendorf Air Force Base and Fort Richardson soon.

But as of Wednesday evening they were warning anyone who lives, works on or visits the two posts in Anchorage not to drink the water due to excess fluoride in the supply.

The water also should not be used to brush teeth and wash or cook food. Any ice cubes made since Tuesday should be thrown out, according to the Fort Richardson Water Treatment Plant. The fluoride cannot be boiled out of the water, according to Fort Richardson medical staff.

The fluoride problem was discovered at about 3:30 a.m. Wednesday at the plant but it is possible that it began as early as Tuesday afternoon, said Bob Zacharski, site manager for Doyon Utilities, a Native corporation subsidiary that runs the Fort Richardson plant, which supplies water to Fort Richardson and Elmendorf.

He and Fort Richardson officials said the fluoride levels in the utility's drinking water are tested daily at noon and were safe as of Tuesday's test.

Early Wednesday, a plant worker adding fluoride to a device that injects it into the water grew suspicious that the system had malfunctioned and was demanding too much fluoride.

Emergency testing determined that the level of fluoride exceeded the state's safety threshold. The utility then notified the bases and began frequent testing of the water and flushing it out of the drinking-water system.

The bases started notifying workers and their families early Wednesday morning about the fluoride problem via phone calls and notices posted in buildings. The bases provided alternate water at dining halls, schools and the hospital.

Some testing by the utility showed that its water contained more than double the amount of fluoride considered safe for drinking. The safety threshold for fluoride in water is 4 parts per million but the utility's water contained as much as 11 parts per million, he said.

It's unlikely, however, that 11 parts per million of fluoride would cause anyone to suffer symptoms associated with fluoride poisoning, said Dr. Paul Friedrichs, commander at the Elmendorf hospital.

Those symptoms can include an upset stomach, vomiting and diarrhea.

One of the worst fluoride poisonings in U.S. history happened in Hooper Bay in 1992, when one man died and more than 200 were sickened. Tests showed more than 40 times the safe amount of fluoride in the village drinking water supply.

Fluoride is added to the water at drinking-water plants throughout the United States, including the one at Fort Richardson, to prevent tooth decay. But fluoride levels have to be monitored carefully because chronic ingestion of fluoride is a proven cause of tooth enamel damage in children.

Elmendorf health suggestions

Do not drink tap water or use it to cook or brush teeth until further notice.

It is OK to use tap water to wash hands, clean food-preparation areas (dry them before using), do laundry and use the dishwasher. Dishes should be dried off before using them.

It is safe to use ice made before 4 p.m. Tuesday and to eat fruit or vegetables washed and dried since then. Any food washed under tap water after 4 p.m. Tuesday should be thrown away.

If you show any of the symptoms of fluoride poisoning (nausea, stomach pain, vomiting and diarrhea), contact your primary care doctor. Go to the emergency room if symptoms are severe (uncontrolled vomiting and diarrhea).