The finding triggered a state and federal mandate requiring the county to send notices to 25,000 customers notifying them about what happened and provide information on the dangers of exposure to lead.

OKALOOSA COUNTY — Lead in quantities that “surpassed acceptable federal levels” has been discovered in four of 30 drinking water samples gathered in August by the Okaloosa County Water and Sewer Department.

The finding triggered a state and federal mandate requiring the county to send notices to 25,000 customers notifying them about what happened and provide information on the dangers of exposure to lead.

Those notices began going out in monthly bills on Thursday.

County officials held press briefings Thursday in an effort to “put the findings in context” and reassure the public that no great health risk exists.

“We want our customers to know the bottom line is their drinking water supply is safe,” said Jeff Littrell, the director of the Water and Sewer Department.

Regulatory guidelines require that water system operators periodically check for the presence of copper and lead in the drinking water, said County Administrator John Hofstad.

In Okaloosa County, samples for years have been taken from 30 randomly selected homes every three years. These samples, prepared by the homeowner, were sealed and sent off for testing.

This year, for the first time, four of the 30 samples exceeded the 15 parts per billion guideline set forth by the federal government, triggering the required notification action.

The affected samples were collected in southern Okaloosa County — Fort Walton Beach, Shalimar, unincorporated Mary Esther and on Okaloosa Island.

County officials confirmed that the high iron levels were found in three samples collected west of Hurlburt Field and one close to Martin Luther King Boulevard and Green Acres Road in the Fort Walton Beach area.

No high lead levels were detected at homes on Okaloosa Island.

Hofstad emphasized the county is certain the lead found did not originate at the Floridan Aquifer, the source of Okaloosa County’s drinking water and “one of the most pristine sources of water anywhere.”

In its news release announcing the findings, county spokesman Rob Brown added “no county distribution mains contain lead,” so the supply line from the county to its customers is also not considered suspect.

The county believes the lead it found likely came from plumbing inside the homes themselves.

All of the homes that are selected for random testing were built between 1982 and 1986. Houses built during that time frame “are more likely to have plumbing which contains trace amounts of lead.”

As Water and Sewer Department Deputy Director Mark Wise explained it, the county in many ways sets itself up to fail when testing for lead because it chooses homes built during a period when lead would most likely have been used in pipes and the welding solder for fittings installed during construction.

Sample collectors are also relying on homeowners to follow the instructions they are given.

One of the four tainted samples was returned at “very high” rates of lead, Wise said. It was a rate so high a retest was taken.

The second test showed significantly lower lead contamination, but still above the federal standard.

Not that it mattered, state and federal regulators don’t permit challenges to their findings, Littrell said.

Stuck with the findings, the Water and Sewer Department has decided to embark upon an Optimal Corrosion Control study. Plans call for stepping up the frequency of testing and a broadening of the random sample pool from "30 to at least 60 homes,” Wise said.

Monthly testing is planned through the end of the year and tests will be conducted every six months through 2018, he said.

“If all is good we’ll go back to once a year after that,” he said.