The Environmental Protection Agency is asking state governments to describe how they are protecting children from excessive lead in drinking water, citing recent problems at schools and day-care centers in Washington and elsewhere.

In a letter released last week, the EPA notes a growing number of reports of schools in which testing has turned up lead-contaminated drinking water. They include the Washington suburbs, where tests this month found high lead levels in some schools in Arlington, Fairfax, Montgomery and Prince George's counties and the city of Alexandria.

Lead contamination problems erupted even earlier in other school systems across the country. Last year, elevated levels were found in public schools in Baltimore and Syracuse, N.Y. In January, Seattle schools turned off their taps and began supplying students with bottled water until lead problems are fixed.

The letter, signed by Benjamin H. Grumbles, the agency's acting administrator for water, is part of a broader agency review of its lead rules. The EPA has been harshly criticized by some members of Congress and environmental groups for being slow to respond to lead contamination problems in the District.

Concern over lead is flaring up again a decade after many schools shut off lead-lined drinking fountains because EPA tests required at the time found widespread contamination. But some water quality experts now say that the focus on drinking fountains neglected other major sources of lead contamination, such as solder and plumbing fixtures that can leach lead even if water is not corrosive.

Municipalities are required to test for lead contamination in residences regularly, but there are no federal requirements for testing drinking water in schools. To these experts, the voluntary testing done recently by school systems confirms that lead remains a problem.

"Anybody that looks is going to find it," said Richard Maas, co-director of the Environmental Quality Institute at the University of North Carolina-Asheville. He said he would expect that 10 percent to 20 percent of drinking-water samples taken in a school system to have high lead levels, with the share fluctuating from school to school.

"The story here has gotten national attention," said Georges C. Benjamin, executive director of the American Public Health Association and the former top health official in the District and Maryland. "What's happening around the country is that people are scratching their heads and saying maybe this is something we ought to be paying attention to.

"But shouldn't we be doing that anyway?"

The EPA stepped up its activity after media reports this year disclosed that drinking water in thousands of D.C. homes had unsafe lead levels, something federal and local officials have known about for more than a year. An interagency team of experts is investigating whether changes in water treatment at the plants that serve the District and parts of Northern Virginia triggered the problems in the city by making the water more corrosive.

But lead problems also have cropped up in suburban Maryland, which uses different water treatment.

Montgomery County School Superintendent Jerry D. Weast said he is puzzled by the test results: Why, he asked, has Fairfax County not found problems at every school it tested, but Montgomery County has? Last week, he asked county health officials to help him determine whether changes in water treatment in the county could be causing or contributing to the problem.

"We're a mirror image of Fairfax County," he said. "Similar buildings -- age and everything else. They don't seem to be having the same problems. That causes me to wonder what is the basis for that."

The EPA letter, dated March 18, asks state health and environmental officials to describe the programs that monitor lead in drinking water at schools and day-care centers. If they do not have a program, they are to outline other steps being taken to control lead exposure.

Schools and day-care centers are of particular concern, EPA officials say, because lead is of greatest risk to infants and young children, in whom it can slow physical and mental development. Lead paint is the largest source of exposure, but water is estimated to account for 20 percent of overall exposure and as much as half in infants who drink formula.

In the late 1980s, the EPA required public schools to test for lead in drinking water. But the agency interpreted a 1996 decision in federal court as barring it from mandating tests because that was deemed the purview of the state.

In response to the problems in the District, the Maryland Board of Education began surveying school systems to find out what they are doing. But Bill Reinhard, a spokesman for the board, said the decision to conduct tests is left to local governments. In Virginia, where the Health Department supervises drinking-water testing, officials also said they have no plans to urge additional testing.

In 1999, D.C. Council members considered a bill that would have included requirements that private and public schools test for lead in the water. It was drafted by Pierre Erville, then a Department of Health consultant, and he said it would have included other lead-poisoning prevention requirements that would have made the city a model for the nation. It died in committee. Erville, now senior program manager for the National Safety Council, a federally chartered education and advocacy organization, called the defeat "very disappointing."

One result of the failure to test in the District and elsewhere, he said, is that "we're at the beginning stage of finding out the extent of the problem. We don't know how to deal with it until we know."

The suburban response to the city's spiking lead levels has varied, with some areas testing every school and some testing none. Montgomery plans to test all water sources at all schools. Prince George's will test all schools but not each tap. Alexandria and Fairfax tested some schools. Arlington tested all schools but not all taps. The District found high lead levels in seven of 154 schools, but those tests were criticized for faulty methodology and will be redone.

Loudoun County and Manassas have begun water-testing programs but do not have results. Frederick County plans to test water in schools. Anne Arundel and Howard County school systems do not plan tests. Other area school systems, including those in Southern Maryland, have not announced plans for testing.

The drinking water issue has also concerned other school systems across the nation. In Seattle, the school system hired a contractor to conduct a comprehensive testing program. Results are expected by mid-June.

Syracuse tested its school water last year at the request of the EPA, which cited high blood-lead levels among the city's children, and found excessive lead at nearly two dozen schools. In Baltimore last year, the city's health director ordered water fountains shut off in city schools after tests found widespread lead problems.

Schools in Boston, Philadelphia and some New Jersey communities also have had problems with lead contamination, according to Erik Olson of the Natural Resources Defense Council, who said there are "serious problems sprinkled across the country."

"I believe a serious monitoring program throughout the country would find it an exception [to have] the system without lead problems," he said.

The testing in the late 1980s and early 1990s was intended mainly to target water coolers with leaded parts, Maas said. Half the problem was fixed when the fountains were removed. But, he added, "They swept the other half under the rug."

Lead can get into drinking water from other sources, including lead pipes as well as lead solder, which was banned in the late 198os, as well as leaded brass and bronze used for faucets, shutoff valves, water meters or other plumbing parts.

"While the lead-service pipes have been shown to be a significant contributor to tap lead levels in the . . . Washington, D.C., case, there are many other potential sources from which lead contamination could arise, both in the presence or absence of lead pipes," EPA scientist Michael Schock said. "Those sources exist in homes and buildings across the country."

Staff writers Lila Arzua, Annie Gowen, Carol D. Leonnig and Ylan Q. Mui contributed to this report.