Does Running Your Faucet Reduce Lead Concentrations in Drinking Water?

Running your faucet before drinking is not a reliable way to reduce lead. A peer-reviewed study of 376 New Orleans homes found that flushing for the commonly recommended 30 to 45 seconds did not consistently lower lead, and in more than half of the homes tested, peak lead levels appeared after that short flush. Lead levels only declined reliably after roughly six minutes of continuous flushing, which is rarely practical. For households worried about lead, an independently tested filter is the dependable option.

What the Study Found

A study led by researchers from the Louisiana State University Health New Orleans School of Public Health, supported by colleagues from Tulane University, Virginia Tech, and Corona Environmental Consulting, found that the currently recommended method of flushing lead from pipes by letting water run before consuming it does not provide a consistently effective way to protect children from lead exposure. The results, published in the International Journal of Environmental Research and Public Health, suggest that in some cases the practice may actually increase exposure rather than reduce it.

According to lead author Adrienne Katner, an Assistant Research Professor of Environmental and Occupational Health Sciences at LSU, flushing water lines for the current guideline of half a minute to two minutes may lower lead in some homes. However, more than half of the homes tested showed peak lead levels in their water after flushing for that length of time. Flushing taps for the recommended duration may therefore raise the likelihood of lead exposure rather than lower it.

Why Short Flushing Can Backfire

The researchers sampled water from each home at several points: the first cold water draw, the first hot water draw, and water drawn after letting taps run for 30 to 45 seconds, 2.5 to 3 minutes, and 5.5 to 6 minutes. Lead levels in New Orleans drinking water were generally low compared to the EPA action level of 15 parts per billion. In 88 percent of homes tested, levels were at 5 ppb or below, though more than half of all samples had detectable lead at 1 ppb or higher. Across samples collected after a 30 to 45 second flush, lead ranged from undetectable to as high as 58 ppb.

Lead levels did not change significantly across the shorter flush durations until the six-minute mark, after which they declined. Even then, Katner notes the reductions were not always large enough to protect children. To bring lead down to the 1 ppb level recommended by the American Academy of Pediatrics, a one-time flush is generally not sufficient.

"We could not verify that a one-time flush is sufficient to maintain low water lead levels," notes Dr. Katner. "Some studies evaluating flushing at school taps suggest frequent flushes may be needed throughout the day, as waterborne lead can return to pre-flush levels within hours."

Prolonged and repeated flushing is also not practical, cost-effective, or sustainable over the long term, especially in cities with declining water resources or rising water rates. The researchers conclude that public health guidance should be updated to acknowledge these limitations, and that a water filter system is a sensible fail-safe for households that believe they may be exposed to lead.

A More Reliable Approach: Filter the Water

Because flushing is inconsistent and the long flush durations needed are impractical, a filter tested and confirmed to reduce lead is the more dependable safeguard. Independent lab testing recorded Black Berkey elements reducing lead by 99.9 percent or more at a 1,000 microgram per liter challenge, and Berkey Phoenix elements, the current in-stock replacement, reduced lead to below 1 microgram per liter at the same challenge level. Full data, lab names, and downloadable reports are in our complete lead guide and on the heavy metals filtration guide.

Frequently Asked Questions

Does running the tap reduce lead in drinking water?

Not reliably. A peer-reviewed study of 376 homes found that flushing for the standard 30 to 45 seconds often coincided with peak lead levels rather than reducing them. Lead declined consistently only after roughly six minutes of continuous flushing, which is impractical for everyday use. A tested filter is a more dependable approach.

How long would I need to flush to actually lower lead?

In the New Orleans study, lead levels did not decline meaningfully until close to the six-minute mark. Even then, the reductions were not always sufficient to reach the 1 ppb level recommended by the American Academy of Pediatrics, and lead can return to pre-flush levels within hours, so the effect does not last.

Is filtering better than flushing for lead?

For most households, yes. Flushing is inconsistent and the long durations required waste water and are hard to sustain. An independently tested filter confirmed to reduce lead provides a steadier safeguard. Black Berkey and Berkey Phoenix elements were both independently tested at a 1,000 microgram per liter lead challenge and reduced lead by 99.9 percent or more.

Does boiling reduce lead instead?

No. Boiling does not reduce lead and can concentrate it as water evaporates. Neither boiling nor short flushing is a reliable fix. Filtration with a tested element is the dependable method.