After the Washington Post ran a series of front-page articles about Edwards's findings, resulting in widespread public concern, the United States House of Representatives conducted an investigation.

The House found that the U.S. Centers for Disease Control and Prevention (CDC) had made "scientifically indefensible" claims in a report that had indicated there was no risk from the high lead levels.

[1] Lead disrupts the physical and mental development of fetuses, babies, and young children, and can cause kidney problems and high blood pressure in adults.

Based on these findings, WASA was required to notify the public and implement plans to replace lead service lines in key areas of the municipal water system.

The first media attention came in late 2002, when the Washington City Paper ran an article about a resident of American University Park whose water tested six to 18 times the EPA Lead and Copper Rule's action level.

[2] As a result, WASA was required to start replacing seven percent of the district's lead service lines each year until the levels dropped below 0.015 milligrams per liter.

[3] In March 2003, Marc Edwards, a professor of civil engineering and expert on corrosion in drinking-water systems, was conducting research into an unexpected increase in pinhole leaks in copper water pipes in the DC area.

[8] The Washington City Paper said that Carol Schwartz, the councilmember who chaired the Committee on Public Works and the Environment, was not informed of the lead issue until that newspaper contacted her during the last week of January 2004.

Nakamura was joined by reporters Carol Leonnig, Jo Becker, Avram Goldstein, and D'Vera Cohn; editor Marcia Slacum Greene provided daily oversight.

District elected officials immediately called for an emergency public meeting, and established an inter-agency task force with the EPA to investigate and manage the problem.

[7] However, messages to the public at the time were often confusing and contradictory: while WASA was suggesting running taps for 90 seconds to flush out any lead, the EPA was demanding that recommendation be changed to ten minutes.

[10] The documents, Nakamura said, "provided a fairly clear picture" that WASA had been trying to find a way to avoid the cost of replacing pipes and adding additional chemicals to the water.

[1] Gloria Borland, a District resident, testified before Congress: "If the [Washington] Post had not exposed this scandal, our children today would still be drinking lead contaminated water.

[21] Michael Parks, director of USC Annenberg's School of Journalism and Pulitzer Prize-winning former editor of the Los Angeles Times, said "The Washington Post's work was a very important piece of journalism—important to every man, woman and child living in the District of Columbia, drinking its water and thinking it was pure.

The report later was strongly criticized, both by Marc Edwards and by the United States House Committee on Science, Space and Technology; see § Congressional review of the 2004 CDC paper.

At an oversight hearing before the House Committee on Government Reform in early March 2004, Marc Edwards testified that his studies showed the change from chlorine to chloramine was the cause of the elevated lead levels.

[31] A report commissioned by the D.C. Council released on December 8, 2004 faulted the federal government's regulation of the city's water supply as a factor in the lead contamination.

[34] On January 21, 2005, the EPA ordered WASA to notify more than 400 homeowners that the agency had mistakenly told them their house's water lead levels were safe, and to replace an additional 500 service lines to comply with federal law.

"[20] At a Congressional hearing that month, the EPA testified that it had no current information on lead levels in 78 percent of the nation's water systems, and that as many as 20 states had not provided any data.

[38] The EPA said that between 2003 and 2005, only four large water systems had unsafe lead levels: Washington, DC; St. Paul, Minnesota; Port St. Lucie, Florida; and Ridgewood, New Jersey.

[27] By January 2005, a year after the high lead levels were publicized by the Post, advocates were calling for the firing of local and federal officials involved in the issue, saying that they had done too little to fix the problem.

[45] In January 2006, the Government Accountability Office released a study criticizing the EPA's efforts monitoring lead levels in drinking water across the United States.

[46] Although the study found that lead in drinking water had generally declined since the 1990s, it noted that data collection problems "may be undermining the intended level of public health protection.

"[53] The Guidotti paper was called into question by members of the DC Council in February 2009, after the Washington Post ran an article about a more recent study by Marc Edwards that found a correlation between water and blood lead levels in area children.

[62] Investigators found that although the CDC and city health department reported dangerous lead levels in 193 children in 2003, the actual number was 486 according to records taken directly from the testing laboratories.

[60][64] Tom Sinks, the deputy director of the CDC's national center for environmental health, told the Post "Looking backward six years, it's clear that this report could have been written a little better.

[67] According to the UAS, Tommy Thompson, the Secretary of Health and Human Services, took the unprecedented step of rejecting a number of nominees to the committee selected by staff scientists.

[67] A 2010 Washington Post editorial cited the group's statement as a reason why the District's lead contamination "was practically inevitable" due to politicization of the CDC.

[64] Jim Graham, a member of the DC Council, said "To now learn that the Centers for Disease Control not only got it wrong but may have intentionally misled District residents and our water agency is the ultimate betrayal of the public trust.

[86] An article published in 2018 by CNN states that the EPA gave the Virginia Tech researcher that found the lead within Flint, MI's and Washington, DC's water supplies a grant to search other major cities.