A timeline of arsenic contamination at the Jacob Riis public housing complex

More than 2,600 residents at the New York City Housing Authority’s Jacob Riis Houses in the East Village could have been exposed to arsenic toxins linked to cancer and skin disorders, officials revealed Friday after samples confirmed the contaminant was present in the water supply.

Residents are still unable to use the water as the city conducts additional testing, and questions remain about when officials knew of the conditions and why action wasn’t taken sooner. 

See our timeline to keep track of the developments:

Thursday Aug. 4: NYCHA officials are alerted about cloudy water conditions at the houses, but do not order testing until eight days later The City reported. 

Friday Aug. 12: NYCHA has the Department of Environmental Protection test for e-coli and chlorine.

Tuesday Aug. 16 NYCHA announces that it’s OK to drink the tap water.

Friday Sept. 2: New York City Public Advocate Jumaane Williams holds a press conference at the Jacob Riis Houses to release a report documenting deplorable conditions at several NYCHA complexes across the city, including mold, pests, service outages and public safety issues.

Friday Sept. 2: New York City Mayor Eric Adams distributes bottled water to residents after 10 p.m., though the public was not yet aware the water supply at Jacob Riis was contaminated with arsenic.

Friday Sept. 2: After 11 p.m., city officials warn residents not to drink or cook with the tap water because it had tested positive for arsenic. The City reports that officials had known about the arsenic for two weeks.

Saturday Sept. 3: At an emergency meeting, residents express outrage that they had been kept in the dark about the water conditions.

Saturday Sept. 3: Manhattan Borough President Mark Levine assures East Village residents there is no evidence of arsenic contamination in the surrounding neighborhood.

Saturday Sept. 3: The federal monitor appointed to oversee NYCHA in 2016, Bart Schwartz, announces a probe into the water conditions.

Sunday Sept. 4: Officials release results of water tests conducted a day prior that showed no elevated arsenic levels.

Monday Sept. 5: Additional testing finds no arsenic, though the mayor’s office still advises residents not to use the water as it awaits test results on 100 additional samples. City officials speculate that the plumbing system, rather than the water supply, could be the source of the contaminant. The initial positive tests were taken at high-rise buildings where the water is routed to a roof tank; the new negative samples were taken from low-rise buildings.

Monday: Residents are instructed to help flush out the system by letting their faucets run for three hours at a time on three consecutive floors.

Monday: The federal monitor orders the city to preserve all documents related to the water quality issues at the complex.