A legislative committee voted along partisan lines Tuesday to accept a bill that would change how Wisconsin municipalities treat their drinking water, a decision which concerned clean water advocates.

The bill, sponsored by Sen. Sheila Harsdorf, R-River Hills, and Rep. Erik Severson, R-Star Prairie, would alter current rules requiring city water systems to disinfect the water they provide to citizens and prohibit the Department of Natural Resources from enforcing the continuous disinfection of drinking water, according to the Legislative Reference Bureau.

The Senate Committee on Judiciary, Utilities, Commerce and Government Operations voted unanimously to approve an amendment, also authored by Harsdorf, to the bill that would allow the DNR to continue requiring municipalities to disinfect their water supplies if data gathered showed water quality, well or water system construction indicated potential health hazards.

However, the change would not supersede federal water quality laws, which could require continuous disinfection at some locations around Wisconsin.

The disinfectant systems used by municipalities are funded in part by the state. The change in DNR rules would have a positive fiscal impact, saving Wisconsin local governments a one-time cost of $634,800 and $130,200 annually on chemicals and new disinfection equipment that would have gone to upgrade the 66 state water systems that are not disinfected, according to the Legislative Fiscal Bureau.

However, the bureau said it was uncertain of the cost to communities if water borne illnesses occur due to a lack of water disinfection.

Opponents of the measure said the potential harm to Wisconsin citizens from this bill far outweigh any savings it would provide.

According to the DNR, the 66 non-water disinfecting communities across Wisconsin have 85,000 residents and disinfection could prevent more than 13,000 illnesses a year or $458,000 in health care costs.

Mark Borchardt, author of the Wisconsin Water and Health Trial for Enteric Risks study, found viruses in 14 municipalities’ drinking water.

“Many scientific studies show widespread viruses in our drinking water,” Borchardt said in a statement. “In my professional opinion, the municipal drinking water systems that do not disinfect have more waterborne diseases.”

Last Thursday marked the 18th anniversary of the Cryptosporidium outbreak in Milwaukee that killed 69 people and sickened thousands.