NEW YORK (AP, NYTIMES) - A blocked sewer main flooded basements of homes with brown filth and left residents in the neighbourhood near New York City's Kennedy Airport feeling sickened by the stench.

A water condition had caused the backup, pushing human waste into about 300 homes in Jamaica, Queens, officials said on Saturday (Nov 30).

Ms Cynthia McKenvie said she woke up around 3am to an odour she thought was a gas leak, only to realise that sewage water was rushing into her basement.

As the water level rose, Ms McKenvie said she raced to move furniture and other belongings, but some electronics could not be saved. After a few hours, she said, her whole neighbourhood was awash in fetid fluid.

"It's messy," said Ms McKenvie, who posted photos showing murky water covering the floor of a basement bedroom and the bottom of a staircase.

"When you open it, it just smells," she said. "It makes you want to vomit. We have to pack up all the clothes."

Mayor Bill de Blasio said crews were making repairs and bringing in pumping equipment to clear up the mess.

The city's water agency says drinking water is safe and unaffected, but Mr de Blasio advised residents to reduce usage to cut down on water going into the blocked main.

Ms McKenvie said she bought two pumps from Home Depot and ran extension cords and a hose to try and clear water from her basement, but the rig hardly kept up.

"There's still some at knee level," she said. "The odour is just unbelievable."

Ms McKenvie said she called 911 and the city's 311 helpline soon after discovering the sewage. A few firefighters eventually showed up, she said, but according to her, none of the city services could stop the flow of sewage.

Most residents in the middle-class neighbourhood are non-white and about half are foreign born, according to US Census Bureau data.

Mr de Blasio says American Red Cross and city emergency management representatives are at the scene to help families displaced by the sewer backup. The city opened a service centre for affected residents at a nearby public school.

The mayor said the city is working to provide hotel rooms to anyone who was unable to return home on Saturday night.

"It's unlivable," Ms McKenvie said. "It's all around the neighbourhood and farther down."

The city's Department of Environmental Protection said the cause of the blockage was still under investigation, an inquiry that was expected to focus on whether cooking grease had been poured down a drain and had congealed in the sewer line in the cold weather.

Mr John Cataneo, an owner of Gateway Plumbing & Heating in Manhattan, said homeowners can avoid clogs by putting cooking grease in the refrigerator to congeal and throwing it away with solid waste.

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Mr Cataneo said he would be surprised if grease from a single home caused such a widespread backup, although it could compound problems with a sewer main. A backup can happen if sewer pipes, which rely on gravity, are pitched at the wrong angle, he said. A blockage can also occur if a tree root grows through a crack in the pipe.

Resident Cardell Hall, 65, who has lived in the neighbourhood for more than 50 years, said the smell was horrendous. "(The wastewater) was up to, maybe, my thighs. I just hope I don't get sick from it," he said.