Detroit schools superintendent Nikolai Vitti is lashing out at a charter school leader he’s accused of exploiting the district’s drinking water crisis.

Vitti on Friday sent a cease and desist letter to Mark Ornstein, who heads the University Prep charter school network, demanding that Ornstein correct a “defamatory statement” he made in an automated phone call to parents this week. Vitti threatened to sue Ornstein and the charter network if he continues to make similar comments.

“You may have heard a report in the media about Detroit Public Schools Community District having elevated levels of lead in the water of all of their school buildings resulting in the shutdown of all water supplies in the buildings,” Ornstein told parents who received the call.

Ornstein, who runs the largest non-profit charter school network in the city, went on to assure parents that University Prep schools have been tested and have safe drinking water.

But Vitti says Ornstein’s message overstated the extent of the problem in the district.

While it’s true that the district shut down the drinking water in all of its 106 schools, it did so out of “an abundance of caution,” after tests showed elevated levels of lead or copper in 16 of 24 schools that were tested this year. That was on top of 18 schools that were given bottled water after an earlier round of testing last year.

The district did not shutdown “all water supplies,” as Ornstein stated. Schools will still have water for hand washing, showering and other purposes.

Vitti suggests in the cease-and-desist letter that the robocall was a deliberate attempt to harm the district’s reputation at a time when district and charter schools compete fiercely for students and teachers.

“If your intention was to share the result of water testing at U Prep buildings … you could have simply referred to U Prep’s test results without mentioning DPSCD at all,” Vitti wrote to Ornstein. “Instead, not only did you reference DPSCD, but you did so in a dishonest, slanderous and derogatory fashion.”

Ornstein did not immediately respond late Friday to requests for comment about Vitti’s letter. A University Prep spokeswoman also did not respond.

Vitti has vowed to put charter schools out of business in Detroit and has used combative language in talking about his effort to lure students back from charter schools.

Ornstein has taken issue with that approach and last year penned a letter to a newspaper calling for cooperation between schools.

“I believe it’s time we end the charter school versus non-charter school rhetoric and join forces as community leaders, educators and parents to devote our energy to improving the lives of children throughout Detroit,” he wrote.

News of the district’s decision to serve bottled water in all of its schools made national headlines and was broadcast widely in Detroit. District supporters noted that the district was smart to be proactive about testing water in its schools at a time when schools are not required to do such extensive testing. Many Detroit charter schools are in aging buildings that may or may not have been tested, but most U Prep schools are in new buildings or buildings that have been recently renovated that are less likely to have issues with lead.

Vitti called on Ornstein to correct the error by sending another robocall that would set the record straight.

“At best your statement was mistaken,” Vitti said. “At worst, it was opportunistic and predatory. In either event, your false statement regarding all DPSCD schools having high lead levels must stop and immediately cease and desist. If such statement continues to be made and circulated, you and University Prep Schools will be subject to legal action.

This is the letter: