The Philadelphia School District has found unsafe levels of lead in about 20 percent of the nearly 14,000 water outlets sampled in the district’s older school buildings, officials said.

The school district has shut off 594 drinking faucets and water coolers after the high lead levels were found in the 298 older buildings, all but one of which has now been tested, district officials told a City Council panel Nov. 20. Many water outlets that tested high for lead were not direct drinking sources, they said.

The district has been providing bottled water to 91 schools awaiting test results, at a cost of $329,000, Board of Education President Pedro Ramos said. Workers have been brought in as early as 4 a.m. daily to flush the water lines each morning to purge lead-contaminated water, an effort that has cost $1.35 million so far, he said.

Councilman Angel Ortiz, however, was critical of the time it has taken the district to address the problem. “The point is, how many kids have been harmed because this process you’re implementing now is 10 years too late?” asked Ortiz, the chairman of Council’s Public Safety Committee.

Lead can accumulate in the body and is particularly dangerous to the developing brains of children. Even low levels may cause a drop in IQ, reduced attention span, hearing impairment, and other problems in children.

The federal Environmental Protection Agency said water samples were taken from at least 60 district schools from 1991 and 1994, but the EPA was not told the results. In March 1998, a citizen gave the EPA test results from water in North Philadelphia’s Bache-Martin Middle School, regional administrator Bradley M. Campbell testified.

The school district did not respond to the EPA’s query about the drinking-water problem, and when EPA officials asked to take samples at the school and review testing records, they were told to get a search warrant, Campbell said. Eventually, the district agreed to allow the agency to review records of lead tests from about 100 schools.

The district is currently testing water outlets in buildings constructed before 1991, when pipes and plumbing fixtures often contained lead. The district has agreed to submit a plan to the city and the EPA by July showing how it will fix the problem, starting first at 50 schools that have yet to be identified.

Mary Jane Hooven, the district’s environmental manager, said the solution could be as simple as shutting down a drinking fountain if the school had enough uncontaminated fountains, or perhaps replacing the “bubblehead” on fountains, which can be a source of lead. In the worst-case scenario, pipes might have to be ripped out and replaced, she said.

Until any solutions are decided, the district is posting “Do not drink from this sink” signs in school bathrooms and preparing educational materials for faculty, students, and families on the hazards of lead, officials said.