(Reuters) - Five homeowners filed a lawsuit against Fresno, California on Friday, accusing the city of letting dangerous levels of lead and other toxins into the water supply and failing to alert the public of the potential danger, local media reported.

Karen and Michael Micheli, Faith and David Nitschke and Jeanette Grider filed a lawsuit against Fresno, its department of public utilities and two contractors in the Fresno County Superior Court on Friday, the Fresno Bee reported.

The homeowners say thousands of residents are potentially facing diminished property values along with costs associated with contaminated water and diagnostic testing for health issues caused by lead exposure, according to the lawsuit posted online by the newspaper.

"The city’s failure to test, report and investigate its issues with its water supply and notify and warn the public of the same is the basis of the defendants’ misconduct," the lawsuit said.

City officials were not immediately available for comment. Fresno spokesman Mark Standriff told the Fresno Bee that city officials had not read the lawsuit and could not comment on it.

In early 2016, the city launched an investigation into discolored water based on reports by more than 300 residents in Northeast Fresno. The investigation found lead and toxins that exceeded the allowable levels in drinking water, according to the lawsuit.

The investigation came 12 years after the city went from using groundwater wells to using a surface water treatment operation, a move that caused the corrosion of pipes that ultimately led to discolored and contaminated water, the lawsuit said.

The lawsuit could become a class action case as potentially tens of thousands of residents may have the same claims against the city, the suit said.

(Reporting by Brendan O'Brien in Milwaukee)