Flushing Guidelines May Increase Lead Risk, Study Says

Guidelines regarding the practice of running water to flush out lead in homes may not be effective, a new study finds.

Researchers from Louisiana State University recently published their findings in the International Journal of Environmental Research and Public Health.

Flushing tap water for 30 seconds to two minutes is widely seen as a low-cost way to reduce lead in water, the study states. The researchers tested this premise in New Orleans, which is compliant with lead regulations, according to the researchers.

The official conclusion, as stated by the study: “While flushing may be an effective short-term approach to remediate high lead, prevailing flush recommendations are an inconsistently effective exposure prevention measure that may inadvertently increase exposures. Public health messages should be modified to ensure appropriate application of flushing, while acknowledging its shortcomings and practical limitations.

Study leader Adrienne Katner explained why the study is relevant to water utilities.

"Utilities are still required to promote flushing so that's one of the problems," she said, per WVUE.

Katner says that flushing may even increase lead risks.

"The highest lead that we found in an occupied normal use home was 58 parts per billion and to put that into perspective 15 parts per billion is the EPA action level, so 58 parts per billion of lead and that was in the 30 second flush," Katner said.

The researchers tested water samples from 376 New Orleans homes, according to a statement from the university.

“Recruited homes met criteria for the potential presence of lead. Virginia Tech colleagues analyzed the water samples, which were first cold water draws, first hot water draws, draws after letting the water run for 30 to 45 seconds, 2.5 to 3 minutes or 5.5 to 6 minutes,” the statement said.

Katner, the study leader, described the significance of the results.

"While flushing taps according to prevailing guidelines (for 30 seconds to 2 minutes) may reduce water lead levels for some homes, over half the tested homes had peak water lead levels after that time, so these recommendations may inadvertently increase exposures," she said.

"More effective interventions like certified water filters should be considered instead, particularly when replacing water service lines and plumbing is not economically possible," she continued.