Durham, N.C. — Excessive levels of lead in Durham's water means the city failed to meet federal safety standards last year. But city officials said Tuesday that the water poses no public health risk.

State regulators last week cited Durham for failing to report the results of water tests conducted last summer.

"I think that our failure to disclose that was a lack of knowledge of the rules and not an intent to deceive the community into thinking that there were no problems with their water when in fact there were," City Manager Patrick Baker said.

Durham was supposed to provide the state with the results of all water tests conducted between June 1 and Sept. 30, but city officials turned over only the September test results, said Laura Leonard, spokeswoman for the state Department of Environment and Natural Resources.

The tests done earlier in the summer included special samples taken while engineers adjusted the chemistry of the municipal water system and special samples requested by customers, Leonard said.

Durham tested water at older homes across the city last summer after a child at a city housing project showed signs of lead poisoning. Eighteen of 89 water samples submitted last fall showed lead contamination above federal safety guidelines, officials said at the time.

Lead is especially toxic to young children and can cause brain damage and other developmental problems.

Durham County public health officials on Monday urged people countywide who live in homes built before 1986 to have their water tested for excessive lead and copper.

Following the state citation, Durham turned over an electronic copy of another 97 water tests conducted last summer. The addition results showed the city fell out of compliance with drinking-water standards.

Baker said the city didn't meet the federal guidelines only because of the way the testing was conducted. The same homes were tested repeatedly, and although the lead levels declined each time, they remained too high, he said.

The city has agreed to have the state test its water every six months, including next month. The move is being done voluntarily.

Under state regulations, cities that fail to meet water standards are placed on a mandatory six-month water monitoring program. If the city has two consecutive rounds of tests that reach standards, it can conduct tests annually. If it meets federal standards for two years, it would then be put back on a three-year monitoring program.

Durham also must review its community education practices and its corrosive control measures.

Baker said the city has changed the chemical makeup in the water, and he insisted it's safe to drink.

"I think citizens are counting on us to do whatever it takes to make their water safe," he said.