The posh High Line Hotel has tested positive for the bacteria that causes Legionnaires’ disease – which has killed seven people in the Big Apple so far this summer — and guests told The Post they were left completely in the dark.

The swanky Chelsea hotel, owned by MCR – the third-largest hotel owner-operator in the US – performed a Legionella test several weeks ago that measured 170 cfu/ml, the number of live bacteria per milliliter of a liquid sample, according to the Hotel & Gaming Trades Council union.

When the union asked management to provide proof of remediation, the hotel, where rooms average over $400 for a Friday night stay, initially refused but finally relented after an arbitration hearing, at which point the workers returned to their posts, HTC leadership said.

The High Line Hotel and coffee bar Intelligentsia on Tenth Ave. in Chelsea, New York. Helayne Seidman

But Rich Maroko, president of the 40,000-strong union, claimed management then threatened to discipline workers if they left the hotel again — despite their concerns about potentially unsafe conditions.

On July 23, the hotel again performed a Legionella test, and alarmingly found levels had increased fourfold – to 700 cfu/ml, raising fears among union members that the levels could continue to grow, HTC leaders said.

Meanwhile, it was business as usual at the Tenth Avenue hotel Friday afternoon — though the majority of staff members were spotted wearing N95 masks in a scene reminiscent of the COVID-19 pandemic.

None of the guests The Post spoke to reported receiving a warning about the presence of Legionella bacteria, or any kind of discount in light of the circumstances. Most weren’t even aware of the situation.

Eddie Avila, a hotel guest in town on business from Miami, was visibly stunned when a Post reporter broke the news to him.

A 3D illustration shows a close-up of blue Legionella pneumophila bacteria. phungatanee – stock.adobe.com

“No, they did not tell me. Oh my God, oh my God,” he said, his jaw dropping before he covered his mouth with his hand in shock.

He said the hotel “definitely” should have been more transparent with guests.

“I’m a little concerned now because, you know, it’s scary! I don’t want to catch anything and bring it back home.”

The entrance to The High Line Hotel and coffee bar Intelligentsia on Tenth Ave. Helayne Seidman

Fitz William Anderson, who lives in Chelsea but visits the hotel cafe 3-4 times a week to work, said management should be notifying anyone entering the building.

He said he became suspicious when he saw the staff wearing N95 masks, and even wondered if there was a COVID outbreak.

“I’m a little concerned because if all the workers are wearing masks — I’m glad to put their safety first — but customers and guests need to know as well,” he said.

The High Line Hotel celebrated its grand opening on Wednesday, November 6, 2013, in New York City.

Willem Wester, a guest visiting from Amsterdam who has stayed at the High Line Hotel several times, said he also wasn’t notified about the presence of Legionella bacteria, and only learned of it through a social media post.

“It would have been good if they told people, but these things happen all the time,” he said.

He said the hotel didn’t offer any refunds for his roughly $350-a-night lodgings, and although he would prefer for management to come clean, he still felt comfortable staying there.

MCR did not respond to The Post’s request for comment Friday.

A general view of the High Line Hotel. The hotel has tested positive for Legionnaires’ disease. Google Maps

In addition to the High Line Hotel, MCR’s New York hotel portfolio includes the Sheraton New York Times Square, Royalton New York, The Lexington, Autograph Collection and the Gramercy Park Hotel.

According to Maroko, MCR properties have some of the worst records for violations following inspections for the deadly bacteria – which can cause Legionnaires’ disease if infected water droplets or mist are inhaled.

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The city is experiencing a breakout of the disease, which has been linked to the cooling towers, which pull heat from water and return the cold water to the system to keep industrial air conditioning equipment cool.

So far this year there have been 92 confirmed cases of the disease and seven deaths, according to the city Department of Health.

Attorney Ben Crump, left, announces a lawsuit in the Harlem Legionnaires’ disease outbreak alongside recovered victim Nunzio Quinto, center, at the National Action Network headquarters in Manhattan on Wednesday, August 20, 2025. Robert Miller

“Protecting the health and safety of New Yorkers is our top priority. The Health Department received a complaint regarding the maintenance of a cooling tower at this location on August 6 and acted immediately to ensure local laws and regulations are being followed. We’ve made contact with both hotel management and the union representing workers and all parties are cooperating to ensure the proper steps are being followed to prevent bacteria growth and protect public health. All New Yorkers and hotel guests are able to continue to use the building systems without interruption,” the Department said.

MCR’s four hotels average 2.84 violations every time the city inspects them, the highest rate of any of the 10 hotel operators with the most cooling tower violations citywide.

Since the city started inspecting cooling towers for Legionella in 2017, records show the citywide average is 2.18 violations per inspection – the High Line Hotel received an average of 6.71 violations per inspection, the second-worst results in the five boroughs.

“No one should have to choose between keeping their job and staying healthy,” Maroko said in a statement to The Post.

“Given the severity of the public health crisis facing the city, our union proactively surveyed the entire unionized hotel industry, and while the vast majority have been cooperative and acted in the best safety interests of workers and guests, this hotel has unfortunately been a glaring and disturbing exception,” he said.

“Now that this latest incident has been made public, we hope they will now take any and all steps necessary to ensure worker and public safety is met.”