The federal monitor overseeing NYCHA directed the agency to preserve all documents related to a probe into the discovery of arsenic in the water supply of a Manhattan housing development.

One of the monitor’s chief investigators, Joseph Jaffe, sent a letter to NYCHA’s chief compliance officer, Brad Greenburg, and general counsel, Lisa Bova-Hiatt, asking for them to confirm their intent to comply with the request.

Trace amounts of arsenic were detected in the drinking water at NYCHA’s Jacob Riis Houses in Manhattan last week, according to city officials.

Residents had previously complained of cloudy water emerging from some taps at the East Village public housing complex.

NYCHA has been subject to oversight from a federal monitor since 2019 after federal officials sued the city for wide-ranging mismanagement.

Mayor Eric Adams visited the housing complex late Friday and handed out bottles of drinking water to residents, The City reported.

One resident told the site that she avoids drinking her tap water at Riis because it’s sometimes discolored and has an unusual smell.

A spokesperson for NYCHA said the organization already retains all documents and records.

“We will continue to be transparent with the public throughout this process,” the rep said.