Disturbing cellphone video shows an ex-con wanted in a water-bucket attack on NYPD cops boldly challenging the detectives who tracked him down in The Bronx — then bolting when they try to place him under arrest.

The brazen display of contempt for the NYPD emerged Tuesday, one day after Police Commissioner James O’Neill fired Officer Daniel Pantaleo over the fatal arrest of Eric Garner in 2014.

The video shows Keith Ford, who’s on parole for an attempted robbery conviction, shouting angrily as three plainclothes members of the NYPD’s Bronx Warrant Squad try to put him in handcuffs, according to a law enforcement source familiar with the incident.

“What is this for?” Ford, 28, repeatedly demands near the start of the 2-minute clip.

When Ford — who’s 6 feet 5 and 255 pounds — shakes off one cop, a struggle ensues and the cops wind up facing off against Ford as he stands with his back to an iron fence.

After one detective draws a Taser, Ford pretends to give up and places his hands behind his back, only to turn and sprint away when the other two cops move in for the bust.

The detective fires the Taser, but Ford appears to yank the barb from his clothing as he leads the cops on a chase down the block and around a corner, with shouting onlookers encouraging him to escape.

The video ends with Ford being placed under arrest against a wall.

The head of the NYPD Detectives’ Endowment Association said the Thursday incident showed “how emboldened criminals have become, thanks to the rhetoric of our phony politicians.”

“It’s the clear example of how indecision from being constantly criticized and second-guessed all the time plays out on the street,” DEA President Michael Palladino said.

“It’s a miracle that these detectives were not injured.”

NYPD Sgt. Joseph Imperatrice, the founder of the non-profit Blue Lives Matter NYC, said the video also offered a vivid illustration of the new normal working conditions for city cops.

“This is gonna continue to happen. Everyone thinks they’re gonna be a reality TV star — they’re gonna film the incident, they’re gonna hope that the cops do their job,” he said.

“They’re going to do everything in their power now to not only resist arrest but give officers a hard time – and you can see it in that video.”

Imperatrice – who last month told The Post’s Miranda Devine that he feared a “Pantaleo effect” could make cops “afraid to their job” – also said that “this is what our politicians want – they want you to walk away.”

“I don’t get fired up, but seeing all this stuff, it gets me,” he said.

“This is gonna set a chain reaction off where it’s almost gonna get to the point where there’s no return.”

Ford was charged with two counts of criminal mischief, obstructing governmental administration and disorderly conduct in the July 21 dousing of two uniformed cops at the corner of Boston Road and East 173rd Street.

That incident was one of several that took place during last month’s heat wave, and which led to criticism of Mayor Bill de Blasio from President Trump and others.

Ford, who also has a prior robbery conviction, was granted $1 bail at his arraignment but ordered held for allegedly violating terms of his parole, records show.

He’s due back in court on Sept. 12.