(CNN) Two lawsuits have been filed on behalf of residents of Denmark, South Carolina, where a CNN investigation revealed that a chemical was being added to the water supply for 10 years without EPA approval.

The city of Denmark has been under scrutiny from residents suspicious of the rust-colored water coming from their taps, even though the local and state government assured them it was safe.

One of the lawsuits seeks to have water bills reimbursed for that time period and alleges that the local government had no right to make people pay for water that was not potable.

Both suits are class-action complaints, meaning they potentially represent all of the nearly 3,000 residents of Denmark.

The chemical, HaloSan, is typically used to treat pools or spas but is not approved by the EPA to disinfect drinking water. The EPA told CNN that "HaloSan has not undergone the necessary evaluations ... and therefore, EPA cannot confirm the safe use of this product for the disinfection of drinking water."

Concerned residents asked Virginia Tech researcher Marc Edwards to test their water supply last year. He discovered that HaloSan was being used to treat the city's water when he read it in a May water quality study done by the state Department of Health and Environmental Control. "I've never once seen it used in a public water supply," he said.

Edwards is known for his work helping to reveal high levels of lead in the water in Flint, Michigan.

The residents say they'd been seeing rusty-colored water for years.

Bakari Sellers is an attorney who filed one of the suits on behalf of residents. He is a former Denmark resident who represented the area in the state legislature and is now a CNN contributor.

The suit filed on behalf of three named Denmark residents, representing the class, alleges that "Plaintiffs were damaged by Defendant's conduct as Plaintiffs purchased and consumed water that included a chemical that was not approved by the EPA and was not determined to be safe to people or the environment."

CNN learned through a Freedom of Information Act request and a one-year investigation that a stop-use order was issued in July, halting HaloSan's usage in the water supply.

The mayor of Denmark, Gerald Wright, told CNN that he did not have a statement at this time regarding the two lawsuits.

"I haven't had a real opportunity to go through it," he said.

But he previously told CNN that he deferred to the Department of Health and Environmental Control regarding the city's water.

Photos: Residents don't trust their tap water Photos: Residents don't trust their tap water CNN's Sara Ganim, left, with Denmark residents Eugene Smith and Paula Brown. They drive 20 miles round-trip to fill empty bottles with natural spring water to use at home. Hide Caption 1 of 6 Photos: Residents don't trust their tap water Paula Brown uses natural spring water to wash her face. Hide Caption 2 of 6 Photos: Residents don't trust their tap water Smith holds a bottle of water he says came from his tap in Denmark. Hide Caption 3 of 6 Photos: Residents don't trust their tap water Denmark, South Carolina, resident Deanna Berry uses bottled water to clean chicken for her family's dinner. Hide Caption 4 of 6 Photos: Residents don't trust their tap water Berry also uses bottled water to brush her daughter's teeth. Hide Caption 5 of 6 Photos: Residents don't trust their tap water The family uses bottled water to make ice. Hide Caption 6 of 6

"It was our thinking that it was an approved chemical to be used," Wright said. "We rely totally on [the Department of Health and Environmental Control] because they have the responsibility and expertise to test, monitor and advise."

The mayor told CNN that the city stopped using HaloSan when it received the stop order in July.

A spokesman for the Department of Health and Environmental Control told CNN it would be inappropriate to comment on pending litigation but previously told CNN that it believed HaloSan was safe for drinking water based on the way its manufacturer "advertised" the chemical.

"The Berry Systems HaloSan treatment unit had been advertised as an effective treatment in the control of iron bacteria and was certified," said Tommy Crosby, director of media relations for the South Carolina Department of Health and Environmental Control.

The manufacturer, Berry Systems, could not be reached for comment.

The Department of Health and Environmental Control and Berry Systems are not named as defendants in either of the two lawsuits.

The EPA confirmed that there is now an active investigation.

Residents like Paula Brown and Eugene Smith have been collecting water samples for years, suspicious of the quality. Now they are taking legal action.

"How can they say it's good to drink?" Smith asked CNN. "I'm not gonna drink it, and I know other people drink it, but a lot of people are drinking it because they have no other choice."

Plaintiffs' attorney Sellers said he had no idea that HaloSan was being added to one of the town's wells. "I was a state rep, and I had no idea," Sellers said, echoing their concerns. "People are sick and tired of it. All they want is clean water. They've had brown water for a long time.

"It's hard to bring in industry because of the water, and I understand the dilemma of the city," he said. "They don't have the resources to fix the problem."

The second lawsuit, brought by attorney John Harrell, was filed against the City of Denmark, along with Denmark's Public Water System. It claims that they are overcharging residents for water, with bills sometimes amounting to more than their rents, "for the poisonous and often unused water."

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In the suit, residents believe they are entitled to refunds with interest. "Defendant relentlessly charged and continues to charge excessive rates," Harrell's lawsuit claims. "Access to water and sewer services is a fundamental necessity to human health, sanitation, and welfare as recognized by South Carolina law."

Harrell told CNN that he has a list of more than 40 residents with health concerns ranging from rashes to more serious kidney and bladder problems, and he is investigating whether there is a link between the water and the health issues. He says he is also assessing whether another suit is possible.

"I am confused by the similarities of the illnesses in the people of this small city," he told CNN. "I am perhaps more confused by the lack of more active pursuit by the local and state government in fixing the situation."

But prior to the lawsuits, Wright told CNN that he's done everything possible.

"I use water every day. Drink it. Washing in it. I would be extremely foolish if I didn't make certain it was safe. I care about myself as much as anybody cares about themselves. We have not been derelict or negligent with anything related to water. Those persons complaining, you will find out they are bogus complaints. We don't have any reason at all to provide anything less than quality water."