DETROIT (Reuters) - Flint, Michigan's lead-contaminated drinking water may still be unsafe, but residents need to increase their use of the system to help speed its recovery, a water expert said on Tuesday.
To properly flush out lead particles and spread the needed chemical phosphates and chlorine that will better protect the system, wary residents need to run the water in their homes more heavily than they have, Virginia Tech professor Marc Edwards, a water engineer who first raised the issue of Flint's lead contamination, told reporters.
The lead contamination levels have decreased since last August, but residents should continue using bottled water and filters, he said.
A top U.S. Environmental Protection Agency official made similar statements last week.
A research team led by Edwards presented its findings, comparing lead levels in the drinking water in Flint houses from March this year to August last year.
Michigan officials have been criticized for their poor handling of the issue, which has sparked national outrage. Under the direction of a state-appointed emergency manager, Flint switched water supplies to the Flint River from Detroit's system in 2014 to save money.
The corrosive river water leached lead, a toxic substance that can damage the nervous system, from the city's water pipes. Flint switched back to the Detroit system last October.
Edwards said if residents, some of whom have drastically reduced their water usage during the crisis, fail to flush out the system with heavy use, the recovery could take longer. In other words, reduced use caused by fear is actually slowing the recovery.
Edwards said the Flint system's recovery time could run months to years, comparing it to that of Washington, D.C., and Providence, Rhode Island, where recovery from lead-contaminated water took 18 months and eight months, respectively. Heavier water use in Flint could reduce the recovery time instead to weeks or months.
"From every single scientific perspective, the more water a resident uses, the better the water is going to be," he said.
Edwards said it is safe to bathe or shower in the water, but to encourage heavier use there is talk among state officials of a two-week period where water would be free. The state previously approved $30 million to help residents pay their water bills dating back to the switch to the Flint River.
Edwards said federal and state officials ultimately need to upgrade the water mains in the system.
(Reporting by Ben Klayman; Editing by Matthew Lewis)