A new round of testing has found high levels of lead in water at more schools in Newark, including at least two charter schools, according to results the school district released on Thursday.

Nearly a quarter of the water samples collected in the school buildings tested last week had lead concentrations above 15 parts per billion, which is the federal Environmental Protection Agency’s threshold for taking action. The Newark school district said on Thursday that 76 of the 324 samples were above that agency’s action level, but that only 16 — or about 5 percent — came from water fountains or other sources of drinking water.

Ten of the 16 sources of tainted drinking water were in a building that houses Newark Legacy Charter School, which enrolls children from kindergarten through eighth grade, the new data show. A building that houses the Paulo Freire Charter School had 12 samples over the federal limit, but only one came from a drinking fountain.