Howard County is among 130 communities nationwide supplying water with unhealthy levels of lead, according to the Environmental Protection Agency, which released a report on the country's largest water suppliers this week.
The water tests targeted county homes that were built in the 1980s, before lead pipes and soldering were banned in home construction in 1986.
Twelve of the 100 county homes tested contained lead levels higher than the federal guideline of 15 parts per billion (ppb). A few houses contained lead contamination of more than 30 ppb, said Michael Giovanniello, deputy chief at the county Bureau of Utilities.
"We're concerned with it," he said. But "the water that's being delivered is of a safe quality. We're delivering good quality water."
Homeowners whose water contained high levels of lead have been notified and their water is being tested again, Mr. Giovanniello said. The majority of the homes -- about 60 -- had water with lead levels under 5 ppb.
The EPA report contained findings of water sampling tests in more than 600 cities and areas nationwide. Ten public water systems, including four in Massachusetts, reported lead levels higher than 70 ppb. Charleston, S.C., was the worst, with a level of 211 ppb. Pensacola, Fla., ranked second with 175 ppb. Howard measured in at 20 ppb.
The local tests were done in the first six months of this year in "high-risk" single-family homes built between 1982 and 1986.
The tests were required under the Safe Drinking Water Act and by the EPA, which has ordered a second round of tests. The county is in the process of retesting water supplies, and if high levels of lead are confirmed, it must begin a program to reduce lead contamination over the next six years.
As a general precaution, Mr. Giovanniello suggests residents run their water two to three minutes in the morning to flush out lead that may have built up overnight. Residents should also use cold water for cooking and drinking.
The county buys water from Baltimore city and Washington Suburban Supply, near Burtonsville, and supplies water to more than 115,000 residents. The county plans to start corrosion tests on pipes that carry water into homes and is publishing an information pamphlet on drinking water.
Pregnant women and the elderly are more at risk of developing health problems from drinking contaminated water, which can delay mental and physical developments in newborns.