Lead-in-water and bacteria levels in the Flint, Michigan, water supply continue to decrease following state and federal interventions over the past year, Virginia Tech professor Marc Edwards announced Friday.
“Citizen-led testing shows water conditions continue to improve. Lead and iron levels in the water are decreasing, with many more homes having non-detectable levels at the tap,” Edwards said during a news conference at Virginia Tech in Blacksburg, Virginia. “However, residents should continue to use bottled water and lead filters until otherwise notified by the EPA or the state.”
A total of 154 of the original 269 Flint homes sampled in August 2015 participated in the fourth round of testing in November 2016.
Results from the most recent testing in November show 43 percent of water samples contain detectable lead at 6 percent above the 15 parts per billion (ppb) federal action level. Results from the initial August 2015 testing showed 92 percent of water samples contained detectable lead with 17 percent above 15 ppb.
The U.S. Environmental Protection Agency’s Lead and Copper Rule requires water systems with lead concentrations exceeding an action level of 15 ppb to undertake additional actions to control corrosion. In late 2015, Flint was reconnected to Detroit water with additional corrosion control chemicals added to the water to help rebuild the protective corrosion scales disrupted during the use of Flint River water.
“The data confirms the system is healing, not only for lead, but also in terms of iron release, which is also much lower,” said Min Tang, of Chongqing, China, doctoral student in the Charles E. Via Jr. Department of Civil and Environmental Engineering.
Additionally, the presence of Legionella and Shigella bacteria in the Flint water supply has also decreased significantly, the Flint Water Study team announced.
Graduate student William Rhoads, of Joplin, Missouri, who led a State of Michigan-funded survey of water quality in Flint homes in June 2016, said continued monitoring indicates that levels of disease causing Legionella bacteria in Flint homes were low in June 2016, and have declined even further.
Sampling results in August and November 2016 indicate continual improvements in Legionella bacteria concentrations, with no Legionella commonly associated with disease detected in November 2016.
Only two of 30 homes sampled in June 2016 were positive for the pathogenic type of Legionella most commonly associated with disease. This is a relatively low incidence of Legionella in the potable water system.
Over the past eight months, a Shigellosis outbreak occurred in Flint. In July 2016 and at the height of the Shigellosis outbreak, the Virginia Tech team collected samples from 30 Flint residential homes. Samples did not reflect any detectable Shigella, graduate student Owen Strom, of Snoqualmie, Washington, said.
The Virginia Tech findings are supported by a recent Center for Disease Control and Prevention Shigellosis outbreak investigation in Flint, indicating that the drinking water was likely not the source of the disease. The most common way Shigellosis is contracted is from person-to-person transmission. Careful handwashing is the most important step to reduce the incidence of the disease, according to the CDC.
Also, earlier in 2016, unscientific testing using nonstandard sampling protocols, raised concerns amongst Flint residents about safety of showering, bathing, or hand-washing in Flint water due to purportedly high levels of disinfection by-products.
With support from the EPA, Edwards, in collaboration with disinfection by-products experts Sue Richardson, from the University of South Carolina, and David Reckhow, from University of Massachusetts, and their teams independently conducted sampling.
“The results from all research teams shows Flint water is just as safe as other potable water around the country for bathing or showering,” said Edwards, the Charles P. Lunsford Professor of Civil and Environmental Engineering in the College of Engineering at Virginia Tech. “The levels of regulated and unregulated disinfection by-products are normal in hot and cold Flint water.”
The fourth-round sampling effort was supervised by Flint resident Lee-Anne Walters, a team of residents, and assisted by Pan Ji, of Xianyang, China, and Christina Devine, of Alexandria, Virginia, both College of Engineering doctoral students. Members of Edwards’ Engineering Ethics and the Public graduate course at Virginia Tech joined the team for a hands-on learning experience.
Edwards’ Flint Water Study team along with citizen efforts are widely credited with helping to expose the city's lead-in-water contamination.
The Virginia Tech team says they will continue to monitor the recovery from the Flint Water Crisis in collaboration with residents, the U.S. EPA, the State of Michigan, the City of Flint, and universities.
More information on Virginia Tech’s work in Flint can be found online:
- Raw HD video and photos from Friday's press conference can be accessed by emailing Jordan Fifer in the media relations office.