Rainwater left untreated in cooling towers atop city-owned Harlem Hospital fueled the Big Apple’s deadliest Legionnaire’s disease outbreak in a decade, the Rev. Al Sharpton charged Tuesday.

A fifth person has died as a result of the Legionnaires’ disease outbreak in Harlem, which has sickened more than 100, health officials said.

Ben Crump and Rev. Al Sharpton will announce a lawsuit against a construction company accused of causing the outbreak.

A deadly Legionnaires' disease outbreak in New York City has set health and community leaders on a campaign to educate the public on ways to prevent the bacteria from growing and spreading.