Residents at some of the city’s swankiest buildings could soon be tossing their own trash and opening their own doors.

Property managers are scrambling to prepare for a possible strike by apartment building workers seeking higher wages, with some asking tenants to prepare to stand-in as voluntary doormen.

Thousands of janitors, porters, handymen and doormen will attend a rally today, organized by their union 32BJ, a division of division of the Service Employees International Union. The public showing comes as their industry contract with the Realty Advisory Board is set to expire on April 20, and workers will vote to authorize a strike if their bargaining committee fails to reach an agreement.

Among the residential buildings staffed by 32BJ are 15 Central Park West, One57, the Plaza, 165 Charles, Via57 West, 252 East 57th Street and the Mandarin Oriental.

Facing the risk of thousands of unstaffed New York City buildings, some property managers have flagged the potential strike with tenants. Others have encouraged tenants to step into worker’s roles.

Residents of the Murray Hill tower the Corinthian were told that if the strike goes ahead, they would have take out their own garbage, rather than use a trash chute, and were asked to volunteer to be doormen.

“None of us looks forward to the prospect of a strike,” read the notice, sent by property manager Denise Lawlor. “Your assistance and cooperation will greatly minimize the inconvenience should a walkout occur.”

TF Cornerstone also told tenants they would have to remove their own trash, and that no building employees would be there to sign off on mail deliveries in the event of a strike.

Dylan Pichulik, the CEO of XL Real Property Management, oversees hundreds of units in New York City, and said that doormen work in a large majority buildings where his tenants live.

“It’s something we are definitely worried about,” Pichulik said. “In anticipation of the strike, we are working with all tenants and sharing revised building protocols.”

He said that if the strike goes ahead, basic functions within buildings will be put on hold, including paging apartments, making repairs or apartment-viewings conducted by agents.

“If the building is able to, they’ll have no more than a super, and a security guard,” he said.

The union, which represents 31,500 apartment building workers in New York City, is demanding higher wages for its workers to match increasing living expenses. Mayor Bill de Blasio and Gov. Andrew Cuomo are expected to attend Wednesday’s rally, which is planned to start at 82nd Street and Park Avenue.

“The workers are prepared to do what they need to to take care of their families,” said Eugenio Villasante, a union spokesperson. “New Yorkers know that they want the wages and benefits they deserve.”

Villasante would not detail the union’s exact demands, but added that negotiations are still “far apart.”

Howard Rothschild, the president of the Realty Advisory Board, said in a letter on Tuesday that the average doorman or porter receives $85,000 in wages and benefits a year while the average handyman receives $91,000 a year in wages and benefits. (The union has disputed these figures.)

In a statement, Real Estate Board of New York president John Banks said the lobbying organization is “optimistic” that an agreement would be reached.

The agreement with workers at commercial buildings expires in 2020.