Who says you can’t air dirty laundry?

When it comes to favorite home-town teams, The Post has the dirt on where the true fans live.

WashClub, an on-demand laundry service in four of the five boroughs, recently completed a survey of the sports-laundering habits of customers.

After all, a sports jersey is a pricey item that can run into the hundreds of dollars and therefore shows a serious commitment to a team.

The conclusion of WashClub’s founder: Brooklynites, not Manhattanites, are in the New York City fans’ winner’s circle.

“Brooklyn fans are the most passionate in New York. That is my belief,” said WashClub’s Rick Rome, a former Wall Street trader.

Mets jerseys are most commonly found in Manhattan’s Hell’s Kitchen as well as Brooklyn’s Sunset Park and Flatbush —where the Dodgers used to play.

One anomaly in this Yankees-centric city: “There are a lot of Boston Red Sox paraphernalia in Washington Heights,” Rome noted. “I think a lot of that comes from Manny Ramirez having grown up and gone to school in Washington Heights.”