In this March 15, 2016 file photo, Virginia Tech environmental engineering professor Marc Edwards testifies in Washington, to examine the ongoing lead water crisis in Flint, Michigan. Scientists say municipal water in Flint, has gotten much better in recent months and is safe for handwashing, showering and bathing. A team led by Edwards provided an update Tuesday May 31, 2016 on results of sampling from homes and buildings in the city, where the water became tainted with lead. (AP Photo/Andrew Harnik, File)

Municipal water in Flint, Michigan, has improved significantly and is safe for bathing and showering, although people should continue filtering the water before drinking it, scientists said Tuesday.

Marc Edwards, a Virginia Tech engineering professor whose testing last summer confirmed lead contamination of the city's water, said sampling in recent months has found that lead levels are steadily declining. Also trending downward are bacteria that can cause Legionnaires' disease, while byproducts from disinfectant chemicals are at normal levels.

"We're seeing some very, very encouraging results," Edwards said at a news conference in Flint, adding that he was "pretty hopeful" the water would meet federal standards for lead content within the next six months. Results of another round of testing expected in August will make the situation clearer, he said.

The economically struggling city of nearly 100,000 has been dealing with poor water quality since switching from the Detroit system, which draws from Lake Huron, to the Flint River in April 2014 as a short-term measure to save money while another pipeline to the lake was under construction.

Residents quickly complained of bad tastes, odors and colors. E. coli bacteria hit unsafe levels. And last September, acknowledged failure to add chemicals to limit corrosion had enabled the river water to scrape lead from aging pipes, exposing people in some homes and schools to the potent neurotoxin.

The city was under state management at the time, leading to an apology from Gov. Rick Snyder. State officials approved returning Flint to the Detroit system in October 2015.

Edwards, who has strongly criticized state and federal agencies' handling of the matter, was hired by the city in January to oversee water testing independently, with his work funded through private donations.

He said Tuesday that resumption of phosphate treatments to coat pipes and reduce corrosion was having a positive effect. A program that provides financial assistance for water use has encouraged people to flush more water through the system, washing away lead-tainted rust, he said.

In this May 27, 2016 file photo Alaysia Carr, spins around as she dances under a fountain-like spray of water coming from a fire hydrant as neighborhood children cool off from temperatures in the high 80's., in Flint, Mich. Scientists say municipal water in Flint, has gotten much better in recent months and is safe for handwashing, showering and bathing. A team led by engineering professor Marc Edwards of Virginia Tech provided an update Tuesday, May 31, 2016, on results of sampling from homes and buildings in the city, where the water became tainted with lead. (Jake May/The Flint via AP, File)

Sampling of water in large and small buildings showed a decline in legionella bacteria readings from October to March, said Amy Pruden, another Virginia Tech professor.

Despite the scientists' reports of improvements, some Flint activists and outside groups remain skeptical. Water Defense, an organization founded by actor Mark Ruffalo, has raised concerns about the safety of water inside hot-water heaters and the absence of government standards for baths and showers. Of particular concern to Water Defense is the presence of byproducts generated by use of chlorine to disinfect water, which in high concentrations can be unhealthy.

Edwards and two other water specialists—David Reckhow of the University of Massachusetts and Shawn McElmurry of Wayne State University in Detroit—said during the news conference their analyses had shown that levels of disinfectant byproducts in Flint water were typical of those in other cities.

"There's nothing out of the ordinary from what we see," Reckhow said.

Edwards said Ruffalo and his team were scaring Flint residents into not practicing personal hygiene, itself a health hazard, based on dubious evidence.

"They're not scientists, nor are they familiar with how to sample water," he said in a phone interview.

In a statement to The Associated Press, Ruffalo said Water Defense has never advised against bathing or showering in Flint but believes more testing and studies are needed before conclusions are reached.

"The people of Flint have every right to demand to know exactly what is in their and to maintain a certain degree of skepticism based on what they have been through," Ruffalo said. "The scientific community, the EPA and the state of Michigan must follow out every possible pathway to contamination until there are answers to the continued occurrence of illness."